If it is just a matter of keeping the bike on the road I have an old (2016 approx) 300wh rack battery, in Winchester. I replaced it a bit ago with a 500wh from Merlin while the price wasn't too bad (as mentioned above), and I was afraid replacement might get very sparse and even more expensive. I think it probably has about 70% or original range; suitable for shortish rides for the next couple of years but no promise.
Reconditioned is a difficult (not impossible) task because the BMS needs to stay connected while replacing cells, otherwise it dies and the whole thing is bricked. I have heard (on this forum) of Torqu-e-cycles (
https://www.torqu-e-cycles.co.uk/) for recelling, others may comment.
Another vote for Merlin if you do want one. Cheap, quick and efficient.
£25 to go to charity. Out of date web page,
https://sumbawanga.org.uk/ Current main project is a bore hole for local girls secondary school. Girls are mainly weekly borders as travel is difficult (not nearly as difficult as it was a few years ago). Water currently has to be head carried for quite a distance.