Treehugger
If a layer of gloss coat looks pebbly, and rough in places, one should be able to knock down the roughness, very gently, using some very fine sand paper. Just try avoid sanding away the paint underneath. A nice thing is, that, when adding a gloss coat, the resulting shine makes the paint look uniform, even if you say sanded the layer of paint as well.

Note: Adding a gloss coat, will make your paint look a little darker. If you add a matte or satin varnish on top of a gloss coat, iirc, the paint will look a little brighter. Warning: Too much matte varnish, and the surface might turn white'ish. Unsure how to fix that, if that happens. I've seen it once with Vallejo's matte varnish. I never tried to fix it, so I don't know more about that. Diluting the matte varnish a little should help avoid ending up with too much matte varnish I think.

Munkyslut
Thanks for the comprehensive advice 😉
The matt/light & gloss/dark info is very interesting.
I can see the merit in the gloss filling the decal edges too, I think I'll practice on one of the rear wings, they are yet to be glued on & easy to rectify if I stuff it up!