Sounds about right. 100 hours at say £100ph, plus around £7500 for a ME CPL. Night rating is 5 hours, ATPL books can vary but almost certainly £500+.
Only advice is don't pay 50% up front. It'll take at least 6 months for the groundschool assuming you're doing it distance learning. They've a chunk of your cash for quite some time. Offer maybe 20% max up front and agree installments at certain points/hours.
Don't forget 14 x £66 for the exam entries.
Also, does the school offer the IR? If not think carefully. Views will differ of course but there are many who would recommend doing the CPL and IR at the same place.