That, of course, is why almost no hangar owner in the UK, located at an airfield where there is a MO present, permits stuff to be done in their hangar
Peter, you need to get out more
You wouldn't believe what goes on in some of our hangars and no one complains
Plus having a friendly MO on field is great if you need to borrow tools of ask questions.
The other option is to drop your plane off with an IA who has his own hangar and can fly you home again afterwards, and maybe help him out a bit (if you want). There are some very reasonable chaps out there.
One big advantage with Non-EASA is the fact that the freelance chap will often work till 9pm to get your aeroplane ready in 3 days and
may not be VAT registered which makes at least 20% difference to the bill. I forget our last annual bill but after being G registered for 5 years previously, lets just say we were nicely surprised (and the annual took about a 10th of the time).