Hi

after very rough quotes (ie is it feasible or not),how much to build from scratch (or an existing lawn at the back of a house – no connections):
1 – std size, single brick garage, tiled roof, couple of windows and power
2 – double length garage, slightly wider than norm with the back half being an actual ‘living’ room on the far end with wide patio doors in one side) and what are heating options (house is a semi and this is intended as loud music/sun room down garden out of way etc)

also
3 – install ensuite bog/shower into a bedroom

Thanks

All depends on area etc.
1) £5-7000ish.
2) £7000-20k (depends on how it is fitted out. A proper living ‘space’ will cost more as it has to be double skinned + insulated etc.
3) Depending on fittings, £1000-£3000.