I also have a huge stock of plastic bags from my click and collect order, some are fairly flimsy but some are the strong bag for life type. I'm hoping my local charity shop will accept them but at the moment they have refused them, their customers have to bring their own bags.
I have problems walking around a supermarket due to arthritis so am planning to continue using click and collect long term. As I also rely on the wonderful staff to put my order in the boot of my car, I think I will continue to have a supply of these bags.
I have significantly reduced my use of single use plastic by buying various silicon products so am unhappy about this but I can't see an alternative.