Oldbeefer, thanks for that link. Nothing found there to help directly but I'll keep searching.
I have done some further research now, apparently HP laptops are by no means unknown to have this type of problem. I have now downloaded a new driver for the built in WiFi adapter; I'll see how it goes next time.
I am thinking of buying a WiFi router for my home PC so that I can use the laptop for the internet, via my own broadband connection. If I buy a complete package presumably the add-on card may also work on the elusive other networks. We'll see.
I can connect to hotel setups (and, it appears, elsewhere -one of my neighbours has an unsecured network!) so the on-board card does work to some extent, just not where I need it to most.
