Consider a basic turbo trainer. New, you can get one for about £80, so with lots moving to smart trainers, you can probably get one for about £25 second hand and out of you student loan.
A couple of 30 minute sessions per week is all you need to keep you ticking over through the winter.
There might be people on here with one to sell if you post something in the wanted section.
Edit: probably a bit more than £25, but a lot cheaper than a smart one.