Do. It.
I just can't recommend the IR(R) enough and I'm very glad I've done it (at just 150 hours total flying time). A few points:
- I would have thought that the IR(R) will be issued in the UK at least until 8 April 2019
- I think that the Trevor Thom vol. 5 on instrument flying should be sufficient - not just for the theory exam but also for the background knowledge for flying training
- With EIR and competency-based modular way towards the full IR(A) now available the IMC course/IR(R) rating is a very good start
You'll enjoy it!
/h88