If I were in your situation I would go and do a night rating. Pay for 3 hours night tuition, then go do 2.7 hours min night flying. Not the best time of year to do it. But if you can find an instructor it is managable in 2 nights of flying.
That will give you PPL + night and all you would have to pay is for 3 hours of instructor + plane.
Also the CAA will want a bit for the extra rating, just short of £80, but don't hold me to that.
You also need to make sure your total hours add up to at least 45, but this can include your night hours