I'm currently looking at
Evans/
Decathlon/
Halfords. I've seen lots of chinese types on
ebay but Im suspicous of quality of the battery and the chargers.
I would be suspicious too. I've not noticed Evans or Decathlon currently sell any good legally-sufficient lights and the only two legal lights Halfords sold last time I found any weren't much good. Like
@KneesUp says, wait a few weeks if you can and Lidl will probably have some decent legally-sufficient battery lights in their next cycling special offer - if you can't wait, post again and I'll go searching for stvzo sets on ebay. For a dark dark towpath, I'd suggest at least a 40 lux mode.
Or if it's usually the same bike at night then definitely consider doing as
@Fab Foodie suggests, and going dynohub. The cost of a cheap dynohub wheel will be recouped in better lights for cheaper (because they don't need all that battery and/or charging stuff, nor fixings that cope with the weight), no batteries and the priceless time saved not faffing about charging or being left in the dark.
I used to suggest fitting an Axa HR tyre dynamo as an even cheaper entry point but few bike tyres now have the dynamo track on the side needed for best results, few bikes have a suitable mounting point, non-damaging mounts seem to have gone up in price and dynohub wheels have come down further in price.