It's a combination of the two Eddie. An extra layer in winter. i.e. a vest.
And I wouldn't consider heating the garage because of £££.
The Yorkshire approach works well........
To be honest Dave with the lack of insulation and probably lack of space to put it in. You would be on a hiding to nothing trying to heat that space.
The only way is with a propane heater as they can do lots of expensive kwhrs but and they would put out lots of dampness.