BGS are an excellent option, couldnt believe how helpful they were, I went after attending another school with little success. Alex Whittingham et al were interesting and patient and the admin staff there couldnt do enough to help me. Its the little things like that that can really make a difference when the exams start.
PS BGS have really good CD ROM programmes that are just as good as those from Oxford (you can get the oxford stuff on Ebay or from Transair and have the best of both worlds!)