Best book / resources for self teaching IR?

[Emkay]

I plan to do multi engine IR training (still for personal / recreational purposes only) at some point in the next couple of years.

I'd like to start reading ahead however and getting myself acquainted with some of the material and procedures

What's the best reading material to get myself trained on theory? Ideally these would be books that I can use during my formal training as well

[Jonzarno]

I suggest that you join PPL/IR which has a lot of resources available to help with this. At the time of writing there are 48 articles about getting the rating and 189 about using it. Apart from that, you can ask any questions you have on their forum and you will get helpful and sensible answers.

[sapperkenno]

FAA Instrument Flying Handbook

[S-Works]

You will need to use the materials from your chosen training provider. So sign up with one and get cracking.

[Reverserbucket]

If you are intending to do an EASA ME IR, I would strongly recommend not reading the FAA Instrument Flying Handbook.

[sapperkenno]

I would strongly recommend not reading the FAA Instrument Flying Handbook

I would agree to some extent with the US specific stuff, but all the info on instrumentation, icing and met etc still apply.

And I speak from experience, having done a US/FAA IR years ago, and recently passing my EASA ATPL exams (none of which helped with actual understanding of how to file IFR and operate IFR within Europe, asymmetric committal heights, approach bans etc) and passing my gold-plated EASA CBIR skills-test a few weeks back (which I thought along with the "training" was an utter crock of ****e - just do NBD holds and test routes over and over until you can fly the test profile with your eyes closed) I'd say the FAA Instrument Handbook is a very useful tool to gain knowledge from.

[Reverserbucket]

There is a lot of good background material in the FAA manual and it's free, however there is also an enormous amount of FAA specific information and guidance in there as well as techniques (look at attitude control and holding for example and you will find different methods described which really need some practical instruction to support). To the uninitiated, this 'wealth' of information will likely prove confusing and overly time consuming without structured guidance.

My opinion based on experience as a UK ATPL/IRI and FAA CFII.
Out of curiosity sapperkenno, where did you do your CBIR?