For arbitrage, jobbing there are plenty of firms.
But if you are good at directional/speculative trading I'll suggest don't go for arbitrage.
Capital base will not be a problem at all, if you are good at trading, rather you'll have a choice what type of contract agreement suits you best.
For Trading Firms contact me through PM with a little detail on your background, I'll strongly dislike if someone associates me promoting any firm.
Cheers.