Thanks Pompa, just downloaded both programmes. I ran Malwarebytes and it only found 2 objects, so I was happy with that! Slimcleaner found a raft of unnecessary files (I told it to leave my frequently used sites alone re logins, so hopefully that'll be OK). I never log out of sites that I use every day, just leave all the tabs open...
Right, now to download the same stuff on DH's laptop.
About 18 months ago I bought an iMac desk top computer because I do a lot of photography and the graphics are so much better. Also, though, Apple doesn't seem to be anything like as vulnerable security-wise as MS, so now we only ever do our banking, online purchasing etc on the iMac.