Shamow
it seems people fall into 2 camps - those that say the IMC is a 'get out of jail free' card and those that say it can be fully utilised, as long as your IMC skills are current
The answer, I think, is that BOTH above are correct. In other words, if you get the IMCR and don't practice it, it won't be much good. But if you practice, then there is no reason why you cannot use it to the full privileges which it gives you.
There is another issue which I may have mentioned previously (I've been away for a few days and haven't had time to read through everything on here): the type of instructor you get for the IMCR matters a lot. Try to find one who flies "for real", one with an IR. They will probably teach you the stuff a lot better than someone who never himself goes beyond the stuff he is teaching.
Regarding costs of planes, you may be lucky at your local airfield as regards groups, or unlucky. I was unlucky so had to buy one! But I did see one plane, IFR equipped, going for £8k for an 1/8 share (which probably reflected its value correctly, compared to what else I've seen). The monthly payment was about £80. On top of that there was an hourly payment for airborne time, about £60/hour including fuel. This made it quite competitive. Fortunately I discovered that the DME was not working and the group had no plans to fix it. Six of them were VFR-only pilots who had no need for it and the other two (IMC rated pilots who routinely flew the local instrument procedure which involves DME, using a GPS as an unauthorised DME substitute...) were selling their shares as a result!! This is what you've got to watch for when looking for an IFR plane. It can be easy enough to find one, only to be trapped in it when some piece of avionics fails and the "VFR-only" pilots refuse to agree to pay for fixing it.
Don't let anyone tell to to not look ahead while still doing your PPL. Some 90-95% of new PPL holders chuck their PPL away almost immediately. The way you are going, you probably won't be one of them - that's a good thing! I was the same, and it displeased most instructors. Most of them don't really like students like that; with the massive dropout rate, they aren't used to it for starters.