At most cases, most ISPs are not blocking the use of the VPN service. That's the purpose of using VPN in the first place. Just a little tweak then VPN should run smoothly. Even in the office, anyone can use VPN as long as users can find a way to install the program on their respective work station.
ISP banning gambling sites are not common on several countries unless the country has a strong stand against gambling and treating it as illegal.
From what country you from?
There are two reasons your country blocking the gambling site or the gambling site blocking your country, our country is very liberal on online casinos and gaming sites but I still find casinos blocking my country, so it's really two way, don't force your way in, it might complicate things in the future with so many online casinos with the best ones accepting the majority of the countries, you'll always have a choice where to play.