Thanks Colin and Ralph.
The canopy was polished to the best of my ability. Unfortunately that ejector mark goes right through the plastic, if I sand or rub much more I won't have a canopy left. So I bit the bullet and masked it up. At least it's not as bad as it was originally, and it's shiny!
I painted the area that will be visible under the canopy, and after that dried attached the canopy using white glue. The wing joins have now been sanded and smoothed.
And because of the size of this model and the overall High Speed Silver scheme, I've rigged up a simple suspension system for drying. Two bent pieces of wire to make hooks; the one in the fuselage is through the stand gap, the other is through the roof of a large box, the holes reinforced with 'bear tape' just in case.
For painting RAF High Speed Silver in the past I've used Humbrol 11 silver with a varnish over the top. It worked well on the Vampires, but on such a large surface area the graininess of that paint (it's much greyer than it used to be) will be obvious, so I've done some research and settled on Humbrol 27001 Aluminium Metalcote (not the polished ones).
Primer should go on today.