Browser you can run on the tor network but it is extremely slow compare to anything else and some sites do not work correctly. This network is designed to be untrackable because there is no central control point. If you can tolerate the slowness it works.
Indeed, a VPN is the best way to access a site privately without your ISP watching over, i I use http://atlasvpn.com/ to protect myself from my provider. Despite the myths, once you connect to a server, your ISP won't no longer see what you do online. But, your ISP will see that you're using a VPN, so you should make sure if it's legal in your country. Of course, you should go for a VPN that doesn't keep any logs. I hope you guys are not doing anything illegal!!!!
I would also recommend a VPN if you wish to hide your internet activity from the ISP. In general I believe VPNs are a must have for multiple reasons - securing your online privacy is just one of them. I personally use this VPN - "Nord" because it seems to be the most transparent about the way it functions and has published numerous reports which allowed users to get a glimpse of all the intricacies of their system: https://www.techradar.com/news/a-look-inside-a-vpn-server