Also you can check out
www.parkers.co.uk for used car pricing and reviews, it's a good tool to use alongside
www.whatcar.com to get ballpark figures for car values.
We're looking at trading in our car right now, and we're looking at Fords (Mondeos or Focuses) and Mazda 6s as our top choices. Husband does most of the driving and it tends to be along dual carriageways and highways, so he wants something that cruises better than our current car, which is fine for cities and shorter trips, but not as good for longer journeys.
Since I've moved to the UK, I've found there can be a great deal difference between manual clutches/gearboxes depending on what make of car you're driving. I did have to learn to drive stick here and couldn't handle hubby's old Renault Clio (the clutch was hell), but I found my driving instructor's Nissan Micra to be a breeze. You will have a lot more choice if you're willing to include manual transmissions and they will more often than not be cheaper than automatics.
Good luck in your search.