is it possible to get a ferry from uk to st petersberg?

there are no ferries that go directly to St.Petersburg, the best you could do is newcastle/immingham to the scandinavian countries.
There are Cruise ferries that do a baltic cruise that include Russia leaving from Dover, they cost a fortune though!

no that isn't possible, not unless you take the Arctic convoys.

From Finland yes. UK, it had better be an Ocean liner "ferry."

that would be wicked. but i dont belive thats possible =) sorry mate.

No, take an airplane first.

There are no longer any direct ferry services from the UK to Russia, but you may possibly get close, maybe to Latvia, Lithuania or Estonia.