Thanks everyone - My bit's and bobs arrived today (including the neck screws) so this evening I enlarged the holes in the body and piloted the neck. A few minutes later the neck was bolted up (it's not really bolted though is it?).
I checked the bridge position for a final time before committing to drilling the holes. Then the bridge went on. I even remembered to put in a bridge grounding wire. I checked continuity and all good there.
I couldn't resist slapping on the junky strings from the kit (two of which broke under tension) to see where things were.
The top E and G vibrate in the nut but adding some tension behind the nut seems to fix it so string trees are in order.
The nut feels a little high but I'm not sure how to measure that. I don't think the slots need to be any deeper so I guess I can take a little bit off the bottom - but I want to experiment with the spare Graphtec I have.
Without measuring it, the neck relief looks okay.
The saddle height is maxed out so of course, the action is crazy high and the intonation needs work but not a disaster.
Generally it feels good - the neck as some chunk to it (which I like) and it seems to sustain pretty well. I haven't done the "back the screws off under tension" trick yet. It also passes the "Slow dancing..." test #modernstairway.
I'm not going to fiddle with the setup until the electronics are in so next I'm going to shield the cavities and then start wiring.
#funtimes
Oh by the way - For anyone in the UK, I've been using https://www.charlesguitars.co.uk/ a lot recently. The prices seem good but they also attempt to minimise packaging by not using the manufacture's boxes for small parts like screws and jack plates - nice.