Which should I use?

Hi, Use rambling roses for an arch, they give a thicker growth, use one each side. Climbing roses tend to send the growth to the top.

But ramblers tend to be more vigorous so you'll have to prune hard to keep them under control!

The arch will have to be quite large and strong for a rambler, they get very large with 10 feet of growth or more each year once they settle in. I'd advise some of the smaller climbers from David Austin roses. They breed some which are really just tall bushes but can be used as short climbers. Check their catalogue for advise of which variety to choose.

Thank you both for that advice. Much appreciated.