Thanks for the replies
So far I've been to motor factors, car parts store, hydraulic pipe makers and couple of local engineeering works. The only tubing with the o/s diam isn't temperture resitant above 80 dg C which I am guessing is just a touch low.
I shall try the link and HEL route, but it looks like I shalln't be going away this weekend now. I hope it rains all weekend but out my window, it's looking like it's going to be nice. Gutted!