I am not on the rock so can't be much help, but I passed my Level 1 in BSL last year, and I hope to go on to Level 2 next year - was gonna do it this year but changed jobs and wanted to settle down, as in Level 2 you need to know the regional differences a bit like accents really, and even though I am located between Preston and Wigan the signs do vary, however to do Level 3 and 4 (interpreter levels) I would have to go to Liverpool or Manchester, these levels are not open to deaf people.
I work with the public and it does come in useful, though as I am not using it frequently I find that I am forgetting it - though I would recommend that we all learn it.
If you do an ebay search you can pick up videos etc, but make sure it is BSL as there are other types of sign language which isn't widely used..... Moon and also Makaton which is mainly what deaf people with learning disabilities have.
How large is the deaf community on the IOM?
Good luck!