hello abbymons welcome to the forum!!!
please check and read this link:
http://www.gov.im/cso/immigration/rules.xml
''All applications for Visa/Entry Clearance to the Isle of Man should be made at the nearest British post (Embassy, High Commission or Consulate) to the applicant’s place of residence. Most applications can be made online and the relevant UK Visa Application Form should be completed. The British post will then forward the application to the Isle of Man Immigration Office for consideration and decision.''
...if you apply for entry clearance you should ask the office you will be dealing with how long it is likely to take to process your application.