It's easy to enable access to all levels. Just copy usr00000.db from the attachment over the original file. On Windows XP it is located in "C:\Program Files\WinLemm\" folder. I don't know where it is on some more recent Windows version. But, it should be easy to locate that file by searching the file name.

I have this downloaded (in time) from Youtube.
Here it is:
https://files.fm/u/v7r57dq5#_

This link it's 2 months only, but you can upload this somewhere else if you like.

Maybe I wasn't clear enough. Amiga screenshots are wrong because on the 'Amiga Lemmings' only play area is 320xsomething and "lemmings number, percentage and time", "skill icons and mini map" is 640xsomething. So, if whole screenshot is in 320x200, resolution of the lower part of the screen is 50% lower then it really is in the game. Half of the pixels are missing.
Of course, at the end it is your decision how you want to show this in the book. And, if you (and whenever) wan't my help with this, just ask and I will be happy to assist you.

As I said, there are lots of mistakes. Certainly, I can't find all. But, here are some of them, and some suggestions/questions (e.g. Why 'New Year Lemmings' game is not mentioned?). Numbers at the start of the lines are page numbers.

17 doesn't mentioned intro in ST version
41 4 pictures from the game (Amiga) in 320x256, should be in 640x200
example how it should be is on the page 250 'X-mas 91 Amiga' and 254 'X-mas 92 Amiga'
43 there is ST version with intro, has 2 disks version, and all 120 levels
45 PC doesn't have 100 lemmings (only 80 max) CD-ROM version is not the same as the floppy version it has CD audio tracks (although version without CD audio also exist), control is also with joy/keyboard
51 CDTV pictures not in 640x200, game doesn't have normal scroll, just fast scroll (used with right mouse button on the Amiga) RMB here is used for some kind of pause (time and animation are not on hold, just the lemmings, suppose this is added to make easier with joypad control)
59 Mac B/W version is included with color version, automatically will run B/W and lover resolution if machine can't run color version
73 FM Towns doesn't have 100 lemmings (only 80), it's more similar to
PC than Amiga version
79 C64 doesn't have 100 lemmings (max 50, in Taxing level 23)
83 CD32 again, not in 640x200
89 Windows version only 80 lemmings not 100,
Fast Forward in not useless, it works normally if PC is not too fast, music is midi, of course it's not the same as the DOS version, it depends on audio card instruments, it's not mentioned that some levels are missing in this version
119 Oh no Amiga pictures not in 640x200
123 Oh no PC not 100 only 80 lemmings, there is CD-ROM version with CD audio but it plays tunes from the original game
125 Oh no Mac B/W version included with color version
127 Oh no Archimedes music - songs are different
131 Oh no Windows not 100 lemmings only 80, not mentioned some levels are missing
153 Lemm 2 Amiga also needs more memory (chip memory exactly) for the full sound effects
155 Lemm2 ST doesn't have intro, but original Lemmings has
157 Lemm2 PC doesn't have the same graphics as Amiga, it's enhanced, controls also with joystick
159 Lemm2 SNES doesn't have the same tunes as the Amiga (only Amiga, PC and ST has the same tunes), many levels are changed, resolution is lower, and has graphics speech effects and snow effect on Polar tribe
161 Lemm2 Megadrive, tunes are changed but only Amiga, PC and ST has the same tunes, some levels are changed, Skier skill is not included, there is mouse support
163 Lemm2 GB doesn't have all the skills, but also have some new skills, many levels are changed
165 Lemm2 Archimedes it's not the only version that requires extra memory for the sound (Amiga also requires), has 10 tunes for Classic tribe
167 Lemm2 FM Towns graphically most similar to the PC, tunes are not somewhat different - completely different
169 Mobile phone version is not "Lemmings 2", it's "Lemmings tribes" completely different game
177 Holiday 93 Amiga resolution of the pictures should be 640x200
179 Holiday 93 PC not 100 only 80 lemmings
207 Holiday 94 Amiga resolution 640x200
209 Holiday 94 PC not 100 only 80 lemmings
221 3D Lemmings PC also keyboard support
248 X-mas 91 Amiga/PC levels 1 and 2 the same, levels 3 and 4 are different
251 X-mas 91 PC not 100 only 80 lemmings, joy/key support
255 X-mas 92 PC not 100 only 80 lemmings, joy/key support
259 3D Lemmings Winterland keyboard support
261 Covox PC not 100 lemmings only 80
267 Prima PC not 100 lemmings only 80
268 skill bar resolution of Amiga should be 640 not 320
New Year Lemmings Amiga is not mentioned
OS/2 version (demo) is not mentioned
also some other demo versions are not mentioned, e.g. Lemm2 Amiga and Lemm2 PC both have some 'new' levels and 'User' skill

You might pay for what? Physical book or PDF? Or you want the physical book for 10 pounds? It wasn't 10, as Flopys said, it was 35.

And, by the way, Flopsy, you didn't bought it a year ago (unless you've bought it twice, but I doubt that). In your post (23 may 2015) you said, "I purchased this book this week". So, it's about 2 years and 8 months now (yes, I know, time flies, it does't look so long ago).

As we discussed about that before, 11 levels are missing.

https://www.lemmingsforums.net/index.php?topic=1467.msg40138#msg40138

Just a few screenshots as a reminder how ports of the game are different (or similar).

Usually it's:
A mere stone's throw - Highland level 4

But on the 8-bit ports it's without (') and it's moved two levels later:
A mere stones throw - Highland level 6


Acorn Archimedes - probably the most similar to Amiga version


FM Towns - with added colors (similar to PC)


Gameboy - monocromatic and so tiny screen


Game Gear - much more colorful but still too small screen


Master System - the same level layout as GB and GG but much bigger screen


SNES - smaller screen than SMS but 'normal' level layout and nice background

8-bit ports of Lemmings 2 are different. As I can see in mu quick check, there are Gold, Silver and Bronze medals, but not Silver or Bronze part of the Talisman. If all medals are not Gold there is no part of the Talisman as a reward at the end. Apparently, it's not given how much lemmings can die on each level, it's how much must be minimally saved. For the Classic tribe, it's like that:

Level   1 - 8 Lemmings
Level   2 - 8 Lemmings
Level   3 - 8 Lemmings
Level   4 - 7 Lemmings
Level   5 - 6 Lemmings
Level   6 - 6 Lemmings
Level   7 - 5 Lemmings
Level   8 - 5 Lemmings
Level   9 - 4 Lemmings
Level 10 - 4 Lemmings

At the end, at least 4 lemmings must be saved, regardless how much of them entered last level. If 8 lemmings entered level 10, then 4 can be lost, but if only 4 entered level, all must be saved.