The Body.
My initial thought was for a butterscotch blonde finish that whilst not a stain was thin enough to see some of the texture below it. I was thinking maybe a few thin coats of interior acrylic paint over a sealer with a clear coat on top?? This is something I will definitely need to look into. Watching some of the Dingo guitar finish videos on you tube with great interest. There are some minor imperfections where the shaping tools have marked the wood, but these will defiantly sand out, and also this is part of the joy of wood isn't it?
Just be aware that ash has a very open pored grain and will require grain filling is you want to have smooth glossy finish. There are numerous ways to do this, but you can decide what works best for you (and with whatever is going over it). Always need to think about compatibility of finish products.
Sanding... and more sanding... it's all part of guitar building. And when you think you're done... sand some more!

Neck fit.
There is a fair bit of lateral movement, however I have seen before members comment that this is desired in bolt on necks so that I can make sure the neck is appropriately aligned before I commit to drilling the holes to fix the neck. The plastic nut was very well aligned, however I have the upgraded bone nut, so I will be looking into how I remove and fit a nut.
A bit of lateral movement is a good thing if you're going to be applying paint and clear coat to both the body and neck. You don't want the fit to be so tight that you have to use force to get it into the pocket. A good fit, it will almost "drop" in with maybe a light amount downward push. And remember, both the heel and pocket are tapered, so install it from the top. Not pushing it in from the end of the pocket.
The nut should come out sideways. Not like extracting a tooth by pulling. A couple of light taps with a drift slightly smaller than the nut and a small hammer should do it. As there's no finish applied yet, it shouldn't be too resistant. If you run into problems, there are ways to work through it, so just ask it's really stuck in there.

Pick guard.
I upgraded to the black bakelite pickguard. It’s fit with the neck is very tight. The interior width of the pickguard at the pocket is narrower than the pocket width of the body. So I may be looking to widen the pickguard where it goes on top of the pocket. Another thing I will look into how I best do that. Oh and I’ll also move the neck pickup onto the upgraded pickguard.
Those kind of adjustments can be accomplished with a set of jeweller's files or even sandpaper wrapped around a bit of wooden dowel.
It's good to have various size dowel on hand just for this reason. Dowel can be a multipurpose material or tool!

Bridge.
The routed compartment for the bridge pickup is not big enough for the bridge pickup to go in. I’m thinking an extra bit for my Dremel is in order and will make short work of making the compartment a tad larger. I will note that I have already purchased some brass saddles from a separate retailer just because, well I couldn’t help myself and decided I liked the look of brass saddles. Will probably go with stringing through the bridge in the first instance, apparently it is a bit more playable on a T-Style than stringing though the body (maybe a project for later).
If your dremel came with a small sanding drum (usually 1/2" or so) you should be able to do what you need with that. Saves you buying another ridiculously-priced bit!
If you decide to go with a string-through, there's lots of options for drilling with a hand drill if you don't have a drill press. I guess cross that bridge when you get to it, eh?