The school should be helpful with general advice. However we have the problem that we have to cover ourselves form immegration point of view - remember 50 Nigerians booking into the British Open Golf and not turning up? Your school has to be sure you are coming on the course, otherwise when people start using you just to get a visa (as we think one tried recently with us) the Home Office will start getting suspiscious about handing our real students visas. Therefore most schools want at least a deposit before they'll write you a letter confirming that you are booked on the course.