Thought I'd update this now my lights aren't being used in anger so much.
I ordered the Vapex 2900s and 1100s and the charger from 7dayshop, doesn't seem to be available now.
Very happy with them, I've recharged once a week and so far as I can tell they all hold their charge as they did when I first had them and all the lights seem as bright as they ever were. I'm running a Smart 25 front and rear (rear on flash) a Crivit front and rear (cheap things from Aldi/Lidl but nice and bright) a Hope Vision One and two rear Smart Lunar R2s (on pulse). Considering how often I would have had to be buying replacement batteries I think I've probably saved myself a decent chunk of money.
Thanks everybody