Can't you just steal bits off Blonde?
More seriously, Planet-X were selling off various fixed rear hubs for £15-30. Name your poison: low flange, high flange, flipflop etc. Something like the following:
120mm fixed-free hub, 32 spokes crossed 3x both sides, Mavic MA3 or Open Sport rim, DT Swiss db ss spokes. Won't be the world's lightest but pretty solid. I run a wheel like that with no problem and am 13.5 stone.
Ratios: somewhere around 70"? That would mean around an 18t or even a 19t. You can of course go a little lower and change up as you get stronger.
Oh and if you change sprockets at home, make sure you get a Hozan lockring spanner. Not cheap but it is a big chunk of Japanese steel: no lockring will resist!