Demolition, site clearance, reduce dig and installation of pre-insulated pipes for ASHP and potential future garden room. The pre-insulated pipe we used in the end was "REHAU RAUTHERMEX 25mm+25mm/111mm DUO PIPE".
The ground was luckily fantastic, apart from one area with some roots and a couple of soft spots left over from the demolition. So we managed to avoid the extra 800mm reduced dig that had been specified based on 2 trial holes in the old front garden. At over 200m2, that would have been a lot of muck-away and hardcore..