I can promise you Norway will not give you this dispensation, UK are quite unique in this situation, they are more flexible than most.
I am 99% sure with your ATPL's in Italy, approved in the UK, you will not be allowed to do it in Scandinavia!
Any may I ask why would you, will be more expensive than in the UK. Your license is issued in the UK, so before doing IR in Iceland, you would need to change your licence to Iceland. (or any other country you choose)
However I don't know why you would want to do this, no economical sense, and making loads of complications for yourself where you licence is issued.
You will need to ask UK CAA or any other CAA, if you can do the IR in their country, with your ATPL theory from Italy.
Issuing a licence, does not mean you can do your IR in the UK, as from the outset IR should be done in same country as ATPL theory. UK is probably the country that will approve your ATPL theory for IR in the UK, Scandinavia is more complicated, at least Norway is.
With regards to Iceland, be careful going to an unknown school, lot's of business in Iceland have had big economical problems.
You will need to make application to each CAA, call them and ask them, they will let you know.
Remember you first need to do the Multi Engine rating and than the ME/IR!
With the apply dispensation, that is what it is, dispensation, and CAA's have to accept this, and most don't accept other nationals except in special circumstances, which you don't have here!