£1500 is about correct. With regards aeros, the most important thing to do is to get you're licence first (and some experience). Some do it on the C152 aerobat, some get differences training tail dragger and do the aeros that way. With regards to weather and December, you can get the best flying days or the worst and remember that as a student, it may be flyable with an instructor, but things like 12 knot crosswinds and 2500ft cloudbase for solo cross countries would rule those days out for you. Its going to be down to the weather, and your ability.
SW