My Norton package expires soon, my provider is John Lewis, who offer the complete Bullguard package free of charge.
Does anyone have experience, I found a couple of online reviews that rate it at 3 out of 5 stars, but then seem to say it does everything right.
Many many years ago Norton produced well regarded antivirus software and utilities. Originally used Norton on my PCs, later Avast and AVG.
Over 10 years since I migrated to Macs now and it's a delight not to have to faff around with antivirus software, though I'm unlikely to be 100% protected just due to the platform.
Macs of course are far from immune to malware/viruses/trojans, it's just that the majority of malicious software is targeted at PC users, or is linked to iffy software downloads or unscrupulous sites that repackage genuine software including 'helpful tools' you'd rather not have.
I believe Avast or AVG (maybe both) were hacked in recent years themselves, so I'd certainly check out good quality online or magazine reviews as the landscape for PC antivirus changes quickly.
Two products which might be worth a look and potentially complementary are Sophos and MalwareBytes.
I only mention Sophos as my corporate IT department use it, and a few years ago they offered free software for Mac, seems they do for Mac and PC with ransomware and other things in the premium product, still potentially good.