And there is your dilemma, professional traders are not spread betting, although I know a few that do so as a sideline to their exchange trading. But to sit in a room of professional trader you must join the club, so to speak. Just as Man Utd wont suffer a Sunday league player in their ranks no professional trading room would have a spread trader in their ranks if for no other reason than as I stated most trading rooms make nothing on the sit down costs, they make a return on the trading. If you sit down spread trading how do they make money? And as you have already indicated if they load their sit down costs then you are better off going into your own office space, but if you go into your own office space you are not sitting with professional traders!
It's time to decide what you want to do, in truth you are probably at the top of the tree for spread trading. We have a huge energy exposure, 8 brokers and 14 prop traders but to join the ranks you have to exchange trade. If you are directional then no problem but if you are just exploiting a loop hole in spread betting then stay where you are because it is not scaleable.