Thanks Tony, yes that site has been mentioned before on this forum & I already have an account with them which I use to buy mainly aluminium angle, small box section & the odd bit of channel. Not much in the way of suppliers local to me for that sort of thing, OK for steel but the guy doesn't sell aluminium. Prices have always seemed to be OK as well although they can be a bit slow with processing & delivery at times.
I had just assumed it was flat bar people were using until I read Jonathans comment about using plate. Same position as you in that I don't have access to any equipment to machine it myself. Been reading the build logs & studying peoples designs, it's the z axis that is the biggest problem for me in that it is sometimes difficult to see what people have done the way the pictures are shown on the forum.