Go for high quality solar panels they work in low light which is important.
Despite the inverters being abler to run beyond the rating I worked out that a slightly larger one worked more efficiently at medium load (which is what you get most of the time)
Get a remote monitor then you can see how the units are doing
Ignore the export meter -it will cost too much
Finally and most importantly you would be crazy to pass up a deal like this. As an overtaxed citizen this is one of the few times the government needs your help and is prepared to pay for it -25years, index linked, tax free and three/four times what you pay for electricity.