I used to do alot of painting with my Dad and two brothers who are all good decorators. Dulux Trade paint is the best IMO. The Dulux trade paint that B and Q sell does seem to be of a different consistency to that purchased elseware. It's a waste of time using false body paints.It may be cheaper but you do need more coats. If you do a lot of painting, you will know how to thin FULL body paints by how much for whatever the situation is, so it covers but also dries flat. I would only use paint with no vinyl for ceilings or if it's the original Farrow and Ball. The trouble is ,you can't 'touch it in' because it shows- you have to re-paint the whole wall. Farrow and Ball paint only looks good if it's brushed on. IMO
Dulux weathersheild gloss system is an expensive system. It doesn't help that the primer is green and you have to use two undercoats!
Zinser primer is handy. Sikkens Paint is quality. Sadolin superdec is very good stuff IMO