As I understand it, there are differences between ICAO CAA JAA and France as regards VFR on top.
I know three definitive rules:
A French PPL can fly VFR on top (but has to get up and down in VMC).
In the UK, you need an IMC rating or an IR to fly VFR on top. A UK PPL is bound by that rule outside the UK - so can't fly VFR on top in France without an IR (IMC not being valid there).
In the US, you need an IR to fly VFR on top.
I don't know if Sweden has filed any "differences" from ICAO or from JAA: the only definitive way to find out is to ask!
It might be in the SE-AIP (maybe that's on the Net somewhere).
For the definitive answer, I'd ask bookworm or 2Ds.