Hi Andy,
hope you did not already bury this thread...
Five weeks or more sounds promising to me, but my stage of planning isn't really more advanced. My original aim was to visit U.K. this year before a visa becomes compulsory to EU citizens
, but I've been left high and dry by a potential traveler with very strict vacation times who was surprised by the ferry fares from Amsterdam to Newcastle around Whitsun.
If I keep on with my plan we could meet somewhere in the south-east, i.e. in Essex to hit the cheap Stena daytime ferry to Hook of Holland. The date could be between June 13th and 20th. Then we have plenty of time to travel to Gdynia either in a straight line or with a huge detour via Denmark and southern Sweden. The latter isn't very challenging, but peaceful and quiet cause high season in scandinavia begins midsummer at the earliest. Finally you could take the likewise cheap ferry from Karlskrona to Gdynia for your own, cause I won't take part in the open'er festival.
Or, if you're not bond to the Bullerby county¹, we could join together in the late of May in northern Denmark to take a ferry to Norway heading up to the fjords, Nordland and the cape, back via Finland and the Baltic States. That nearly ensures empty roads and campsites but can be cold as hell.
I'm from Berlin, Germany, in the mid of forties (felt 15 years younger) and I've have some experience in travelling by bike (identical to yours) mainly in eastern and northern Europe. My English skills may vary from day to day and from acceptable to broken.
I try to avoid Autobahnen (direct german translation: car ways) as like as motorways and any boring road at all. I like single carriageways, single track and gravel roads.
I'm scared to get squeezed by giant motorhomes at lotted campsites and I don't need attractions like karaoke or similar. At very heavy rain a cabin is preferred to the tent pitch.
I love ferries in general and nighttime ferries that do not vomit me in the early morning, in special.
That's all for the moment,
would be glad to hear from you!
Holger
¹
https://en.wikipedia.org/wiki/The_Six_Bullerby_Children