This is an outstanding website for your driving theory tests.
As many other reviewers have noted, the tests are significantly tougher than the actual BTT, so that you are over prepared by the time you take the actual test.
I got a 50/50 on the actual test, pretty much after practicing the 10 tests on this website + a bit of reference to the latest book.
Completely worth the money - if one merely does all the tests and learns from the wrong answers, one should be able to sail through the actual test. No other prep required.