BackPacker. You'd need a better mind than me to work out whether any UK IMC rating you do now will ever lead to any useful qualification you can use in the Netherlands under EASA in the future. I think the general consensus (and I am sure to be corrected) is that that the IMC rights will be grandfathered by EASA allowing local licensing authorities to add additional privileges to licenses so that equivalents of the national ratings can be maintained.
Whether you could do the course in 7 days is a good question. When I did mine, there were two of us back seating each other’s lessons. Generally we would fly two sorties each per day. You'll probably find that at the beginning two hours per day is enough as it is quite hard work. Once the basics are grasped you could probably managed three per day. The only problem with Jan and Feb will be the number of light hours in the day... Not sure if you can combine the night rating and IMC, or whether if you already have a night rating whether you could do the IMC training during the hours of darkness.
I'd highly recommend giving the folks at Bournemouth Flying Club a call; I may be a little biased, but I have done all of my training there and completed everything in minimum hours and with positive feedback from the examiners. They are a nice bunch of people too!