It depends on what sort of trip it will be. Will you be wild camping or travelling from one capital to the other?
The different countries all have different laws, but slipjoints and SAKs are legal all over Europe. That being said, the risk of you being stopped and searched is practically zero if you stay out of trouble and give drugs a wide berth.
A slipjoint such as the Spyderco UKPK combined with a SAK will go a long way in an urban environment. As a matter of fact, a SAK will probably be all you need. If you want pliers, then the Leatherman Knifeless Fuse is a good one coupled with a knife too.