A UK national or citizen needs only a passport to travel to Isle of Man. And you can directly contact the passport office.
Visit Passport Office
If traveling through sea you need a valid passport with a minimal fare charges whereas, if traveling through plane one needs a special photographic identification.
Here is a list of people who don't need a visa for traveling to the Isle of Man:
a) If you have a multiple entry English visa
b) You are a Permanent Citizine of UK (ILR)
c) You have a certificate of entitlement to right of abode.
People who need to apply for a visa of overseas territories include people who are on a visit visa, study visa or on a work permit visa. Follow the steps if you need a visa to travel.
a) You can apply online for visa. (link for applying online)
b) Complete the form and after filling it, take its printout and sign it.
c) An ID will be given by the agency to you.
d) There is a visa application and processing fees which you can pay via credit card.
e) Forward the application to visa agency of your country.
f) Now all you have to do is to wait for the response by the authority.
Country travel advice:
In order to get familiar with the culture of the place check out the following "Link"
Things allowed to the tourists during their stay:
walks, fishing, cultural heritage, railways, golf, bird watching, sea sports, movies, cycling, wildlife park visits, etc.
It is advised to apply for travel insurance so you are ensured of your safety while making the visit.