I'm in North Kent, been using Daler-Rowney foam board, will have to give the Hobbycraft stuff a go as the DR stuff is quite expensive, their black version is very strong though, much stronger than their white.
Newark half way between Nottingham and Linclon
on the a46 where the A1 and A46 cross me and friend trying to find a friendly farmer who will rent us a field to turn into a local flying club.
For foam board try art discount they sell 20" X 30" in boxes of 25. http://www.artdiscount.co.uk
Kendrick