try hub le bas in Leicester, they do 1 inch tube in 3mm wall iirc, they may also do 25mm. I would go with inch stuff because it's cheap, easy to bend and you would need pretty good eyes to tell it from 25mm. Hub le bas have a minimum order charge that means you need to spend about £150 in total, (inc delivery) but you are going to need a couple of sticks at least to build the rack so you won't be far off.

