Maybe Building Regs .. that's about all.
Much cheaper to convert that space than attic space, but do check foundations are same as building, not a lightweight add-on.
Not usually, Boxy .......... same "Class of Use".
Unless you're in a Conservation Area, Matt.
Definitely Building Control though. Cheapest and easiest way is under a "Building Notice".
Assuming the garage is attached, or integral.
Most likely to be cheaper than the loft option.
Where I live the garages that were built with the houses are actually a very tight fit for modern day cars, so the majority of people around here don't use them for parking their cars and a lot have been converted into habitable rooms. We ourselves did this 2 or 3 years ago. We didn't need planning permission, but did needing Building Regs Approval. Our builders did have to dig deeper foundations than they would have liked in order for it to be passed off.
Just check whether there is an Article 4 direction on your property, or any previous planning permissions for the house itself or any extensions, as these could have a condition specifying the garage has to be retained for parking vehicles. if not, you won't need planning permission but you will need Building Regulations approval.
if or when you have plans drawn up ( i had to) i was advised to call it a utility / play room or similiar,the planning people seemed happier with it.Mine was in fact a dining area/office/study.
chas - which is your planning authority? sound like nonsense to me, we wouldn't even ask (in the rare cases where you even need planning permission to convert a garage!)
Bushbaby ............ I think Chas is maybe confusing Planning with Building Control.
If certain B/Regs requirements can't be met. It's often, as you know, the case that use has to be "restricted".