I did my IR in Arizona, USA.
2 weeks of incredibly hard work, so hard I was ready to chuck it all in on every single day. And that was for a 500hr pilot who had been flying IFR for 2 years on the IMCR, and had been flying some airways around Europe for a year (with a RHS pilot who had an IR but knew next to nothing about IFR flight planning) all without any difficulty whatsoever.
I had also done the written exam in the UK beforehand.
There are N-reg planes that can be rented but they are rare. Normally, one does an IR to fly distances around Europe, and most people that do that are owners. An IR doesn't really make much sense for the self fly hire scene - for starters, most G-reg SFH planes are not even airways legal.