Even if you never use the IMC rating in its legal definition, it is some of the most valuable training you can do in the british weather, especially if you do any cross country time. I was like you and unsure whether to spend the money a few years ago, I did, and I can think of more than a few flights where it has added a safety margin in deteriorating weather. Even though I'm now overseas and the ticket is no longer of use, I call on those skills once in a while. The only danger - never expect the skills to be there when you need them without continual practice!