The foam FT uses is 5mm thick and is a 20x30" sheet, some of the other UK guys say that they have a similar foam in the UK but its heavier which likes to make models tail heavy. Hopefully one of them can help with the specifics of that. As for motors, ESC's, and servos I can find some on cheap chinese sites like Banggood that will work, but I can't at the moment since I am on my school laptop (curse the internet filter!) If someone hasn't already I should be able to get links for you once I get home. In general for the simple cub you're going to want 9 gram servos and I think anywhere from a 20-30 amp ESC. If you look up the motor FT uses in the power pack B and then search for that on Banggood they should have it. If not I can find a suitable one once I am home.
I hope this helped, and if you have any further questions feel free to ask. Most of us don't bite
I use the A1 foamboard from Hobbycraft and yes, it's noticeable heavily than the Adams board available in the states.
My simple cub fly's quite well, but it's about 50% heavier at its flying weight but it does cope well with wind and I get about 8 -10 minutes on a 3S 1500mAh battery.
Using a 2212 1000KV motor swinging a 10x4.5 E prop
I can get 4 sheets of A1 foam board from Hobbycraft for £10.....I do actually enjoy the process of scratchbuilding. I live with the weight difference knowing the board is far tougher than the flitetest stuff. I noticed the Leeds Model Shop carry some flitetest kits and plain foamboard too - I may get the mighty mini Spitfire from them - just for fun!!
Transmitter is a choice you have to make, there isn't just a go to transmitter for everyone. If you're looking cheap and works well then the flysky i6 is perfect for that. If you know that you're going to expand in the hobby and don't want to have to buy another transmitter down the road then a spektrum or taranis transmitter would be better. If you plan on going the latter route I would suggest doing some research before purchasing either.