Personally I would stay well clear of the free software
I agree spending a few pounds on AV is a sound option and having a hardware firewall is very wise too.
I would still ask what tangible difference is there between the free version and the paid version of AV software? With most, if not all providers, it's only functionality within the program and not lesser protection. Therefore, from a security perspective, the free version of AV is as secure.
The biggest security threat to any system is the operator![]()