What you might want to do is find the UK IMC rating syllabus. There should be official documentation on the UK CAA website, and there are books on the subject as well, typically available from places like afeonline.co.uk.
You then take this documentation, shove it into your instructors face and tell him "this is what I want to do". Forget about the exam, just make sure your flying is up to UK IMC standards.
The UK IMC is to a very large extent what you're looking for. It doesn't do a lot with regards to take-off minima, SIDs and that sort of stuff, but it does teach you how to fly on instruments when you get into cloud en-route. Including partial panel, upset recover and partial panel upset recovery. Obviously it covers radio navigation. And it covers precision and non-precision approaches to a runway, either to land or as a cloudbreak procedure so you can continue VFR below the clouds.
In the UK, it gives you the privilege to fly IFR outside controlled airspace, and in class D. But it doesn't allow you to fly airways, and you also do not have to learn about high performance/high altitude stuff, or weird weather patterns near the equator or the poles.
There are pilots who use their IMC rating on a daily basis, but for most pilots it's a "get out of jail for free" rating. And that's exactly what you seem to be looking for.
The UK IMC rating is only legal in the UK, and that's the only place where you can do the official training and exam. But any IR instructor should be able to teach you the syllabus unofficially, and the skills you gain are applicable worldwide. Oh, and the training is 15 hours vs. 40 (or 45?) for the full IR.