Why do you think a VPN is necessary?
VPNs will reduce the likelihood of a (different) third party seeing which sites you visited. For example if you are with BT, they will not be able to see the list of sites you visited if you use a VPN but if you are visiting a banking site, the data between your device and the bank is encrypted regardless. Absent of a VPN, BT could see that you visited your bank but they wouldn't be able to see which pages you visited on the site.
I use free wifi in pubs. If the pub is dodgy, I will use my phone as a hotspot. Again, the dodgy pub will only be able to see that I went to the bank, but not which pages or the traffic. That said, the dodgy pub could redirect traffic from my laptop to a fake version of my bank's site, and from there they could let me enter my details in the dodgy bank site and then quickly knick and use them.
I use VPNs from time to time, but primarily to bypass geo-location restrictions.
It should be noted that the VPN can see which sites you have visited. Again, they cannot see which pages on the site.