Yes you can enter Montenegro with valid 2 years UK visit visa for up to 30 days without a visa The answer is from the official Montenegro Ministry Of foreign Affairs website:
--- Overview of visa regimes for foreign citizens ---
Holders of travel
documents containing a valid Schengen visa, a valid visa of the United
States of America, United Kingdom and Northern Ireland and the
Republic of Ireland, or a permission to stay in these countries, may
enter and stay, or pass through the territory of Montenegro up to 30
days, and not longer than the expiry of visa, if the period of
validity of the visa is less than 30 days.
Holders of travel documents issued by the European Union Member States
or the United States of America, Kingdom of Norway, Republic of
Ireland, Swiss Confederation, Canada, Commonwealth of Australia, New
Zealand and Japan based on the Convention Relating to the Status of
Refugees (1951) or Convention Relating to the Status of Stateless
Persons (1954), as well as Travel Documents for Foreigners may enter,
pass through the territory of and stay in Montenegro up to 30 days
without a visa.
Mere possession of a visa does not grant the entry to Montenegro.
Other legal requirements for granting a foreigner the entry and stay
to Montenegro must also be met according to the Law on Foreigners
(“Official Gazette of Montenegro”, no. 56/14 , 28/15 and 16/16.
Visa regime between Montenegro and other countries is regulated by the
Decree on visa regime (“Official Gazette of Montenegro”, No. 35/16).
Visa in itself does not offer a grant of permission to work in
Montenegro. Person who intends to work in Montenegro must obtain a
temporary residence permit for the purpose of employment or seasonal
work, on the grounds of previously issued work permit.
Also, the holder of an ordinary Indian passport needs a Montenegro visa: