Since i cant visit Betfair itself due to restriction but i do made up some search and here's
the countries which are banned. Dont know if this one is updated or not.

Canada
China
Cote D’Ivoire
Cuba
DR Congo
Eritrea
France
Greenland
Iran
Iraq
Israel
Japan
Lebanon
Libya
North Korea
Portugal
Somalia
SudanTurkey

Source: https://www.cheekypunter.com/faq/betfair-country-restrictions/

Just like Quidat mentioned above on why would go or still use if you are restricted?