Hello, I had the same problem as Wann, but I found a way to partially fix these issues in C2 (and while I haven't tried it yet, I'm fairly sure you can also use this method for C1). This is by no means a perfect solution, mainly because it is quite time consuming as you have to manually edit a bunch of single files, and it only translates back the game's interface (such as the kits' windows), but not the in-game content, so the words your norns will learn on the computer will still be in french. However, this is good enough for me at this point and I figured I'd share it with other players here until someone finds a better solution.
From what I understand, if your operating system is in french, both C1 and C2 will automatically install in that language. While I couldn't change C2's default language to english, I did find a way to trick the game into thinking the english version is actually the french version.
First you have to download a program that allows you to edit .exe files called Resource Hacker
http://www.angusj.com/resourcehacker/.
Using the program, go to your Creatures 2 directory and open one of the .exe files, for example BreedersKit.exe. Now you should see all the folders inside that file on the left (Bitmap, Icon, Menu, and so on). In some folders there will be a bunch of files called 1031, 1033, 1036, 1040, 1043, and 3082. Each one represents a different language. 1036 is for french, and 1033 is for english. All you have to do (although it
does take some time) is to delete the files named 1036 by right clicking on them and selecting "Delete Resource", then right click on the files named 1033, select "Change language", and rename them 1036.
In every .exe, the 1033/1036 files are located in the following folders:
Menu
Dialog
String Table
240 (this last one is only found in ObservationKit.exe)
There is no need to look into the other folders, as they only contain pictures.
Please note that I never managed to edit launcher.exe and start.exe. They do contain 1033/1036 files, but when I tried to edit them, the game wouldn't start.
Now the game's interface and all of your kits should be in english. Hope this will help at least a little. :)