You need to ensure that your home is fully insulated and energy efficient. It's pointless generating your own energy if you lose most of it through gaps in windows and un-insulated walls and lofts. For the domestic RHI, you will need to get a Green Deal assessment, and if this shows that you can install insulation, this must be completed to receive the RHI payments.
You need a heat meter installed, to measure the amount of hot water your solar thermal system generates. Energy Jump will install this for you as part of your system.
The domestic RHI tariff will be paid at 19.21p/kWh of renewable heat gerated for 7 years
The commercial RHI tariff will be paid at 10p/kWh of renewable heat generated for 20 years
Domestic RHI at ofgem's website
Non-Domestic RHI at ofgem's website