Can you use Homebriefing for a VFR FPL UK to France or within UK... I say again VFR FPL?
Yes, been doing it for a few years. Less so recently as I use IFR for abroad but Homebriefing will file a FP from anywhere to anywhere, and are
AFAIK alone in all the web based services willing to confirm this in writing.
They charge Euro 36/year but recently have changed their scheme and have put a limit of I think 10 or 20 per year on the # of FPs that they will accept outside of their home country (Austria). They will probably be charging a few Euros per FP after this figure - still very cheap as it is hugely convenient.