On Wednesday, 28 August 2019 15:26:14 UTC+1, Andrew wrote:
At only one metre gap, could you use overhead conduit with T&E inside it?
Do you mean core drill the garage and house and have some 38 mm
conduit,about 1.5 metres long going right through both walls (*)and
dead level (and siliconed in ) ?.

It wouldn't have to be level, and you could have an inverted U if you want more headroom. Surface box on wall, conduit up over and down to surface box on other side.

Steel conduit costs, but is quite highly reusable, or of there's little risk of it being damaged PVC conduit might be acceptable. The main thing is it would avoid SWA.

Owain