I found this thread on the topic:
http://www.quiltingboard.com/main-f1...nd-t65211.html
Here is a link to what we normally use in the U.S.:
http://www.amazon.com/Elmers-Washabl...dp/B000Q3KHCM/
The key points here are that it is white and washable (meaning it washes out of little kids' clothing!).
Here is a link to Elmer's washable blue gel glue:
http://www.amazon.com/Elmers-Washabl...hable+blue+gel
Is that the one you are looking at? It seems to me it would work too, but I haven't tried it myself so don't know for sure. Seems to me it would be safer to order the white school glue that most of us use.
Edit: I know in the thread there was some talk about mailing the glue to the U.K. However, I'm not sure this is possible nowadays because of all the restrictions on liquids in postal packages.