I am investigating sending off my old candles, no longer required, to a company in Exeter. They melt down and recycle the wax as well as recycling the glass/metal containers so one doesn't have to bother about separating those.
Hopefully we will get to Devon soon - I have several friends to visit so can make a trip to Exeter with my stash. In the Bath area is a drop off point but I can't find anywhere else in the UK. A question I will ask.