Ive recently did a dissertation for my degree on renewable energy solutions and will be doing a similar thing myself, although ill not be going the solar panel route. Solar panels are a good energy efficient method of offsetting your electrical bill, but the payback time for the initial cost is not very good, even when selling electric back to the DNO.
However if you were to look into solar heated water systems then you will get your payback much sooner. Especially when you consider gas is more expensive the electric, so the saving is larger.
I will add though, that there are alot of companies who 'specialise' in this, but they are bodgers putting in cheap systems without expansion vessels etc. The main issues with them are when you are not using your hot water (ie on holiday) and the glycol within the evaporated tubes gets so hot it ruptures the pipes. A good system will negate this issue but obviously cost more.
Alot of people in the 'know' think Air Source Heat Pumps are where the future is heading. Currently renewable energy grants do not cover them, but in the future its widely believed they will come under the scheme. The units can also be specified to heat your water as well.