OK - just to let others know for the future if in similar predicament.
Ended up going for Dulux Satinwood (water based) - got this mixed in B+Q (pick white off the shelf - choose your colour). Applied with Paint Sprayer so was a bit heart in mouth. Made sure thinned it enough for the sprayer first. Fantastic result - no runs - nozzle didn't clog - worked a treat.
Went for "Jet Black." Nice and solid - got chap in the store to put few extra dollops of the pigment in!
Only thing I'd advise is go for a 1 Liter can. I worried that wouldn't have enough + bought a 2.5l can. Did one entire pass on the cab and probably used 1/10th of the can!
Oh, also - choose your primer/undercoat well as well if spraying. On hindsight - think I chose a bad one to use with sprayers - nozzle/airjet holes kept getting clogged - dried paint in the nozzle felt latex-y.
Final finish wasn't piano-black smooth, but I quite liked it - uniformly slightly bumped (bit like the finish on coin doors) - gives it a nice solid looking texture. Like a hammered finish:

(This after one coat - coat 2 tomorrow!)
Hope this helps someone in the future!