Benny, in my experience they're true to size, but the lasts I've had tend to be pretty long - a classic English extended toe. So if your foot is narrow, you might find them big. If it's wide, they'll be fine but maybe a touch tight across the toe. They do a wide fitting in most of their sizes. But yeah, for an average width foot, they should fit just right, just maybe with a slightly longer toe sticking out than you're used to if you usually wear American shoes.
In your case, it sounds like a 5.5 would be too small for you if you normally take a US7. But shop around. Check out www.herringshoes.co.uk if you like Church's - they always have some clearance items, and you can search by size. I would suggest a 6.5F is more likely to fit you. They are also very helpful with recommendations and shipping - I'm wearing Church's I bought from them as I type, and I've had several other pairs from them too. Try their own brand made by Cheaney too - very good value.
N.B. it's easy to get mixed up about width fittings in English shoes:
Loake, Barker, Alfred Sargeant, Cheaney, CHURCH'S: E= Narrow F = Medium, G = wide. Church's also do H= extra wide for some shoes
Edward Green, John Lobb, Crockett and Jones, Gaziano & Girling: E= Medium, F = wide
Tricker's: some stuff to do with numbers, I think 5 = medium!
So don't get caught out: F is regular width for Church's i.e. US D or M width.
Edited by mimo - 2/21/13 at 12:55pm