I really appreciate all the advice Mcc - it's all been really useful.

I think I'm starting to climb the curve on this one. My last two coats have been a lot cleaner I think mainly due to putting a lot less on. The sanding has helped although I think there's a bit more todo - but I'll leave it another five or so coats.

I've changed my technique a little to control how much is going on the rag. I'm using those spray paint mixing cups, which I guess are maybe 2/3 pint so they are quite deep compared to the opening. So getting a controlled amount of poly on the rag was quite hard. So now my approach is to fold the rag as you suggested an then hold against the side of the cup. Then I can tip the poly up the side of the cup and onto the rag rather than dipping it into the poly.

A margarine tub with a lid would better so I'm going to switch to those for the next batch. I got about 8 coats out of the first. The temps here are quite cool (~10C) which seems to be keeping it okay.

Yeah I'm confused about the fumes - Of all my YT vids watching I don't see anyone apply poly with a mask. But it's definitely effecting me. I got a cheapo painters Darth Vader mask yesterday and it's much better when wearing that. I could try changing to a different white spirit but I'm conscious of changing too much mid job.

There's so many different skills to learn when building a guitar for the first time. It's like one guy trying to build a house - he's got to be a bricky, a chippy, a spark... If I can make a guitar that's playable and doesn't look like it was finished by a five year old using a shotgun then I'll be very happy!

Oh... and the Gotoh bridge arrived yesterday - it's definitely a lot more refined than the kit bridge. Everything lines up apart from the two holes at the front - but I'm confident I can make it work.