The reason I asked about your plans for the UK was just to know where you're leaving from, as some places are easier to reach from some places than other. If your trip had ended in Scotland I would have suggested a short trip across the north sea to Norway and continue from there. But from London there are many more options.
However I'm still going suggest that you start in Bergen or Stavanger. There are direct flights from London, but if you want to rearrange the trip in the UK and end in Scotland there are direct flights from Edinburgh and Aberdeen that will make it a bit easier.
A rough suggestion for two months:
Bergen, Norway in a Nutshell to Oslo. Train from Oslo to Trondheim with a stop in Røros.
Train from Trondheim to Östersund, a night in Östersund and then Inlandsbanan to Mora. A couple of nights in Dalarna (don't miss the Zorn museum and his house!) and then train to Uppsala. A couple of nights in Uppsala and then the overnight ferry to Helsinki.
From Finland, take the ferry across the gulf to Tallinn, spend a couple of days in Tallinn and include at least one day trip. Tartu is well worth a visit. Then take the overnight ferry to Stockholm.
Spend a couple of days in Stockholm. Then take the ferry to Gotland. By now it should be mid August so the peak tourist season on Gotland will probably be over. Spend 2-3 nights (or more) in Visby. Then ferry to Oskarshamn and bus to Kalmar.
A night or two in Kalmar, then continue by train to Copenhagen. Add a stop in Lund or Karlskrona on the way if you want to see a bit more of southern Sweden. After a few days in Copenhagen continue to Hamburg. Either direct or spend a night or two in e.g. Odense or Århus on the way.
From Hamburg I'd suggest a more eastern route via Berlin-Leipzig-Nürnberg to Munich. But you can also choose a more western route if you want to get to Geneva. From Munich you can take the train Innsbruck and stay there if you want a short visit to Austria and then take the train south to Bozen and you are in Italy, and the German-speaking part of Italy.
That should be doable in two months.
There also used to be a cargo boat from Goole (England) to Sweden
which you could book on as passenger one way which transited the canal
but I don't think that they still take passengers.
I'm not familiar with that route, but there are no boats between the UK and Scandinavia anymore. There is a freight route from Gothenburg to Immingham that runs pretty frequently but they don't take foot passengers anymore since someone in charge decided to not provide the needed facilities for foot passengers in Immingham.
As mentioned above, the possible routes in northern Europe are almost endless. The route above is just a suggestion.
Also, two months in northern Europe and one month in Italy sounds like you're getting dangerously close to the 90 day limit. With Russia and Ukraine being off limites there are few options for leaving the Schengen area in northern Europe, but during your month in Italy you can consider taking the ferry across the Adriatic and spend a few days in Albania or Montenegro.