Does anyone here work at a builders merchants.
I need to buy some Corrugated Sheets to replace the ones on my garage roof as they are leaking.
good call m8, need some meself same reason but shed roof, lol.
Wickes used to do them, not sure if they still do
M.P.Moran & son in kennington are the cheapest and you can haggle with them
one in east ham called jessops that could help 
Pyro