This could all be answered waiting for the OP to post their BT Wholesale checker results.
Chances are they're not on an EO line, so they'll be able to get an FTTPoD quote. If so:
1. they can get a free desktop quote; this usually takes about a week
2. they can then pay £250+VAT which triggers a survey, and get a confirmed quote, which could be substantially lower or higher than the desktop quote. Then they have 30 days either to pay the balance to complete the order, or drop out and lose the £250+VAT.
Typical confirmed prices for "easy" FTTPoD installs seem to start at £8,000+VAT these days. Collected quotes reported by forum users here: https://docs.google.com/spreadsheets/d/1QFkK1sLBFQjl...
There's no guarantee on installation time either. Likely to be 6-12 months, but up to 18 months is not unknown.