Yep. My google skills so far have turned up SDP who's prices are not really very good and diynot which is a forum for exchanging info on this sort of thing. Oh also Plumbase are doing a "fill your boots" sale on copper pipe at the moment which seems pretty good.
I need an apex steel lintel above 4m bifold doors topped by fan light glazing. Any recommendations? Catnic, Keystone, Ig, Other? Would you get more than one quote?
The idea was to match the existing tiles and then change the lot in 15 or so years (if they lasted that long). I might consider getting new tiles and doing the main house roof at the same time we put the extension up.
I should think I'm quite a bit more intelligent than you chap, not usually considered hard of thinking by those who know me. I didn't at any point consider mixing the two systems on one zone even though I know very little about heating systems, unlike you who can easily tell the difference...