Thanks for the advice! I did try with gloss varnish and PVA glue, results were almost identical. Gaps are now filled.
Not a lot painting during the last couple of days (and by not a lot I mean none), due to having guests at my house the whole week. I only managed to prime two models that I will paint next. I tried zenithal priming for the first time, I will check if it makes any difference when painting.
On the plus side - my HobbyZone stuff arrived so I finally managed to get my paint rack and paint station sorted out, no more mess!
Those 2 minis are almost identical and I would paint them both at the same time as I used to, but this time I will try a different approach and paint them seperately, that way I can fix any mistakes I did on the first one and try some other techniques and see what looks best.