building control wont let you re-use windows unless you can prove they meet the current thermal regs (unlikely unless they are less than approx 2 year old)

obviously you can re-use windows in non-habitable rooms like workshops/garages/stores.

re-using bricks, its a PITA to clean the old mortar off. its do-able on old bricks which are very hard but on 60's/70's houses onwards you've got no chance, they will explode when you start trying to whack the old mortar off.