Cost of whole house renovation and a 10ft by 8ft extension

Received the pricing from Harry the builder.  It's much more expensive than I expected.

One story 10ft by 8ft extension: £15,000
Garage convert to an en-suite room: £10,000
Total rewiring: £4,000
Total re-plumbing, un-vented hot water system and new Vaillant combi boiler.: £4,000
Install new bathroom: £3,000
Remove paper from whole house: £1,000
Replace doors of the whole house: £1,000
Painting and decoration of the house: £3,500
Outside Fascia Board: £1,000
Total £42,500

I guess this doesn't include VAT.  I don't include the kitchen units and bathroom units.  That's means the total project cost will be over £70,000.  And this is only one-storey extension.  This is way over what I want to pay for.