Hi JP,
You have not stated your nationality nor the aircraft category that the rating is for which would be helpful.
Although there is a number of CFIIs in Europe and they can do training towards the FAA Instrument Rating in Europe, the TSA requirements regarding the training of non US citizens for certain training events still apply even outside the US.
Independent CFIs can register with the TSA and be approved to accept foreign students, however the student will need fingerprints to be taken by an approved person ( list on the TSA flightschoolcandidates website ) and there is limited choice in Europe. This may present a barrier to your training plans.
VFR