So I know this question has been asked the other way round, but I'm in the UK and I'd like to make a solid American IPA, and I'm wondering what the best UK malt would be to replace US pale ale malt for this purpose. I've heard that staple UK varieties like Maris Otter don't quite work well. Does anyone have any suggestions? I should also add that I don't know of any means to get US malt in the UK, so import over the Atlantic probably isn't possible, even if I wanted to...
You can try Muntons Pale Ale malt - it's a good solid base that's fairly clean and doesn't bring oodles of that soft biscuit maltiness and complexity that you get with the Maris Otter malt. It's highly modified, so well suited to single infusions and has good diastatic power so you can add adjuncts to the mash also.
Being a pale malt rather than a lager/pilsner malt, you'll still get some malt backbone, just not so "in your face" as with the MO. However, since US 2-row is quite "dry/grainy", and you might want your IPA to be "just hops" then you could try using a good pilsner malt, which will contribute the least flavour from the malt. Personally, I'd go with the pale, since you need a little malt to stack the hops up against.
FWIW, all these malts are "2-row" - although barley strain does contribute something, the primary difference between the US and UK malts in how they are handled by the maltster.
I've brewed with US 2-row and Muntons, and to be honest, unless you're comparing them side by side, it's going to be difficult to discern any difference in something as hoppy as a IPA. (EDIT: My LHBS just stocks it as Muntons Pale malt - when I got the 25kg sack, I remember now it was Optic. So the suggestion you have to use Optic seems on the mark.)
For more anecdotal evidence comparing grain flavours, (source)
English 2-row pale | Briess 2-row pale | Marris Otter | Belgian Pale Ale
Generally, "flavor" increased as you moved down the list I put above. There were subtle differences in all of them. The English and American 2-row pale were nearly indistinguishable except the american had a slight "grainy" flavor.