Selling the property may become a problem as you're supposed to have some sort of "certificate of conformity" these days I believe. Qualified installers can issue one themselves as long as they're following the rules. A self-install would probably require dealing with the local council's building control department (and a huge amount of faff to put together all the paperwork they'd require). Either way you're not likely to get one unless all the necessary rules are met.
If you're not likely to be selling for a couple of decades or you're only planning on leaving the property in a box and you're happy for it to be your heirs' problem then I imagine it doesn't matter that much as long as you don't burn the house down either
James