Depends on what you're trying to achieve. If you want to be more employable, unless you have something lined up that needs it, an extra rating doesn't make much difference; 5 hours of (say) turbine might as well be 0 if it's not in an immediately useful type (i.e. one that your new employer uses). An IR is probably good, although at the moment, it probably won't make any difference.
If you're just looking for something fun, for your own, personal interest, and don't care about anything else, then what you do is entirely up to you! I personally really enjoyed my IR, and found it interesting and entertaining. I'd like to think I'd spend the £38k again, even if I wasn't looking for improvements in my job prospects, but who knows. I will say that a type rating isn't a whole lot of use for its own sake, unless you're planning to actually fly the type from time to time, so it's probably worth picking something you have access to, if you're looking for an interesting additional type.