Before the 13th December is it totally FREE, survey, admin, instulation everything but after that date the goverment has or will lower the buy back of electricity to 21kw(43kw at moment) so the companies are not going to make such profits hence then charge you for instulation, panels and other things.
Pimm - not strictly correct - some may charge for it after that date but its unlikely.
The funding for the supply & installation is largely from banks and investors - they will still get a better return on their money, so the advice is that it will still be free fitment etc