I found this, accordingly you may have to pass your test in the UK soon, then you will be able to get normal insurance, that will get cheaper after you pass your driving test here. Moral of the story is, always check your insurance costs, before buying a car.
COMING TO THE UK FOR MORE THAN 12 MONTHS?
International students coming to GB for more than 12 months
If you are coming to study in GB for more than 12months you may only drive on your valid foreign licence or international driving permit for a period of 12 months from the date you first arrived in GB to take up your studies. If you want to carry on driving after the 12-month period, you must obtain a provisional GB licence (which will allow you to apply for a driving test) and pass a driving test before the 12-month period elapses. You can apply for a provisional licence (on the D1 form that is available from the Post Office) once you have been resident in GB for 6 months. If you do not obtain a provisional licence within the first 12 months of your stay you must stop driving at the end of the 12 month period until you have obtained a provisional licencse.