Why you want to do it in Scandinavia?
UK is probably much cheaper, at least compared to Norway!
But the big question is, where is your ATPL theory from? What country CAA? Because if this is not in the country you plan to do your IR, you will need to apply for dispensation in both countries, where you sat your exams, and the country you plan to take your IR.
I know Norway is not very helpfull with this, UK you should have less problems. Believe me, Scandinavia is not as easy with paper work as you think.
A good affordable school in the UK is Stapleford Flight Centre, IR is around £12.000 and the ME is around £3.000. ME done in Seneca, and ME/IR done in DA42 sim and aircraft.
I can tell you, Norway for sure is not the place to do it, will cost you a fortune, and the Norwegian CAA is tough work, half the people do not know the correct regulations and paperwork.
However, first thing is, where did you sit your ATPL exams, under what CAA country, if that is not a Scandinavien country, I would tell you that you probably have no chance to do your IR there, normally must be done in same country! (Air Law - Lasors)