I've used Excel Edge a few times now, they do an aluminium and steel edge restaint. Your contact up north is James Dalrymple 01743 464153 or at http://tinyurl.com/5mqu4d. Its a great product at a good price.
Alistair
Hi Sharon, firstly good luck with the new business. I'm sure you'll do well. Secondly there will be quite a few suppliers on the net - 5m rolls come in about £10 - £14 but why not try your local metal fabricator/ engineering for corrugated galvanised steel they may be able to supply cheaper. Good Luck