The way the block discounts work is that the quoted block, say £5000, buys you the standard 45 hrs which is the legal minimum for a JAA PPL.
If you then take 60 hours, you will pay the £5000 for the block, plus the hourly rate for the next 15 hours.
Plus landing fees, exam fees, books, bits and bobs, etc.
Block bookings may be tempting but schools go bust regularly and you invariably lose any un-flown entitlement at that point. The funds are not held in escrow but are used to keep the school afloat, and are perceived to increase student commitment to finishing the course.
If somebody recently did a JAA PPL for £4000 all in, I would like to see a breakdown.