Findyourwings, its a real problem getting the dosh together for flying. BUT...
amazingly, January is often a good time with sometimes a high pressure lingering over the British Isles...ask a weather expert if there are other calm weeks over the winter....
Why? because you want to SAVE your money up and then fly five days in a row, or at least four, and then you will make real progress. With same instructor of course. Possibly several hours, with a lunch break, each day.
O yes it will cost a lot for that week, perhaps your bank manager would cooperate, or the flying club make a special arrangment, never hurts to ask.
What I am getting at is the best way to progress is to have a lot of instruction in a short time. Winter is often a good time because flying clubs are not often so busy in the winter. And light aircraft usually have HEATERS anyway! Further more as thermals are rare, the air is smoother, and the air is thicker, being colder, so aircraft performance is much better...Wright Brothers found that out right away. (Kitty Hawk in Jan. better than Ohio in July!)
Anyway, flying only once every two weeks with different instructors is guaranteed to make you feel worse than the frog in the well.
Good luck! Let us know how you get on.