I wish I did have a larger workshop! The garage is about 21 x 8 feet, but is adjacent to the house with a single pitch roof, which provides plenty of storage in the garage rafters. I can access either end, and it leads through to the utility room. I might have to use that to lay up the floor/ballast tank top.
The trailer is going elsewhere so I can put a build cradle on the floor, which will be on castors so I can get to one side or the other of the boat.
The buoyant foam for the floor of the ballast tank sheds dust everywhere (whenever you touch it). I've put that in a neighbour's garage for now, hoping to use it all before too long.
The current plan is to cut and join (and seal and sand) as much plywood as possible, taking care to make the planks the right way around (because there's no way to turn a 17 foot plank around without going outside). Then the trailer is going into storage, I will then build the cradle, and start assembling the hull. If things get desperate I'll have to do jobs outside, but given the great British weather I'd rather not.