The Instrument rating at white waltham is £2500 and the night rating is £160 per hour and 5 hours is required which is £800 so all in all it adds up to £10,000 right?
I don't think you'll find a school offering a £13k Instrument Rating for £2,500.
For £2,500 you're looking at an IMC.
So;
£6,500 for PPL
£800 for Night
£2,500 for IMC
£9,800 leaving you with a couple of hundred pound toward your class 1 medical.
Then you'll need to hour build and sit your ATPL exams, then the expensive bit which is a Multi-IR and CPL and an MCC to top it off