Well Pete, it might determine where you live? Since you have not indicated what part of the world you are in, you might want to check your local jurisdictions. If you're going to remove your garage door, you will likely need a permit. If you leave the door in place and put up an internal wall, in the side of the garage door, you'll likely not require any permit. So keep it looking the same on the outside and you're likely not to have any problems. You'll basically be building a box within a box so proper internal electrical service will be required. That's better left to an expert master electrician. (I worked as an Electricians Helper in my later teenage years which helped me do the wrong things the right way, he he.) I built my Remote Truck utilizing a power isolation transformer with step up/step down capabilities. No ground. Just 110 V & 110 V hot leads from a 220 V single phase drop. Sometimes, 104 V & 104 V hot leads from 2 drops of a 208 V/3 phase drop. Internal grounding was from the center tap of the 2 individual secondary output windings. The internal construction is all wood along with the outer construction negating anybody's chance for connecting with ground inside the control room/studio. And a lot of electricians don't even quite understand what I've done. LOL because they know nothing about audio. This was a tip from my friend K00STER McAllister from Record Plant Remote, NYC and also how he has his truck wired. Of course, like myself, that transformer may set you back $1000 US (available from Signal Transformer Company, USA) and it's worth every penny. Early on, I was able to operate the truck without that transformer but it was nightmarish and ground loops aplenty. You'll also be amazed at how much quieter your equipment will be since it is a quasi-balanced power distribution scheme as well. And that is one of the most fundamental and important considerations you should be considering. There are other balanced power devices already available prebuilt that are available in a wide range of current requirements. Some from just 20 W up to 7.5 kW which is what I use & 10 kW which KOOSTER uses.

Also remember not to tie your power amplifier grounds to your microphone & line input grounds/output grounds from its speaker outputs. That's a big no-no. Powergenerating device grounds should be completely separate from your audio grounding. The exception here is that your power amplifier AC power cable ground should still be connected to a central ground point where all of your other internal electrical grounds are also terminated. Just not the speaker output grounds. They stay isolated and go directly to the speakers if you are not using powered monitors.

I'm electrically enhanced
Mx. Remy Ann David

As long as the house isn't a rental and you don't change the exterior, can replace the interior back to its former "glory" if/when you move out and you won't disturb the neighbours, away you go I'd say!