SE are right. Each electricity customer will have to pay a small extra amount on each bill to their supplier which will be passed into a central account (a process called levelisation). This amount will then be distributed back to the suppliers for them to pay to each FITs customer based on the kWh they have generated.
None of this will be financed by central government - other than indirectly to facilitate various parts of the mechanism via OFGEM, Gemserv, etc.
I wonder what will happen to my nPower juice account - 100% offshore wind power? I predict a riot signing up for green electricity if it is rightfully exempt from the "dirty tax".
-Paul