So, a little bit of an update in terms of planning.
First and foremost, I think I've found my neck:
Starcaster maple neck on ebay UKSeems like a decent quality neck, and it's about in the price range that I want to go for.
Additionally, I've decided I'm going to buy a plain pickguard sheet, cut it to shape & size, and paint it light blue to go with a glossy bright orange body.
When this painting will take place, I don't know. Probably not any time soon due to the weather. However, what this does mean is that I can get on with the electrics, filling in cavities, etc so that's a bonus. Plus if I spread it out over time, the costs involved don't seem quite as dramatic