Where can I get Styrofoam in the UK cheap?

[Basefrog]

I'm thinking of making a DIY background for my 29g tank. However I can't seem to find any stryofoam in any of the shops I look in Anyone had any luck anywhere in the UK?

Many thanks!

 

[Okelly]

Ask in shops they often throw it out places like currys and supermarkets..

 

[leopardfrog]

Try b&q they have it in the insulation section in the larger stores