single sided FR4 boarding

I'm in the UK and I want to buy some single sided copper boards for home manufacture of PCBs. The size I want is 250mm x 130-140mm. Can anyone recommend a supplier please?

Does it have to be FR4? That is normally only used for high frequencies. Anyway these people have PCB

as do these

If it's not FR4, then its most likely phenolic, which can seem like cardboard.