There used to be a document (from memory, it was Standards Document 26) on the CAA website that listed all flight schools known to the CAA, and what types of training they could provide. From memory there were only six foreign schools that could do PPL-type stuff. One in Jerez, Spain, four in Florida and one in California.
Unfortunately with the transition to EASA that document no longer exists and is replaced by standards document 30 and 31, which only lists UK facilities. (Both are available here:
List of Flight Crew Standards Documents | Publications | About the CAA) So if there's an exhaustive list of foreign facilities that can do the IMC (or other PPL-level courses), then I would love to know about it.
I just checked the Jerez website and it seems they focus on commercial stuff only. If they can do the IMC for you, then the website doesn't mention it.
FTE | Pilot Training | British Airways | Flight School | Become a Pilot | Pilot School | FTEJerez Maybe Bose-X has more information...?
Anyway, the remark of Cobalt is a valid one. I guess I was lucky. I did my IMC recently at Leicester Aero Club, on an intensive course running Sunday to Thursday. The initial two days happened to be in VMC conditions, using foggles, but on Wednesday we did a three-hour cross-country to Norwich while an occlusion was coming through. We spent almost all of the three hours in solid and turbulent IMC, doing two ILS approaches and an NDB approach to actual minima. I really learned about flying from that, and gained a lot of confidence as well.