To do it overland I would try and get yourself to Izmir in Turkey from here you should be able to get a train to Istanbul. From Istanbul you can get to the Netherlands or Belgium. Don't try and go via France as there are rail strikes on at the moment. Ferries to the UK are running from Amsterdam to Newcastle and Zeebrugge to Hull, Zeebrugge to Rosyth, Hook of Holland to Harwich and Rotterdam to Hull. Most of the Ferries have spare capacity for foot passengers. The ferries I have mentioned will cost a little more than the Dover to Calais crossing but then you have to take on the French rail strike!
There could be an option to get a ferry to the Greek mainland, then get a ferry to Italy, from Italy you would get a train through Austria and Germany, I'm not quite sure what ferries there are from Rhodes to the mainland but I would expect your hotel can share some light on that
These routes will take about 3/4 days! Some airports are opening but with so many people displaced it may be worth doing the overland route, it depends on how much of an adventure you want! I think it’s better than hanging around an airport.
Ferry tickets and rail tickets can we bought via our site for most of your route. Have a look at the maps of ferry routes http://www.flightlesstravel.com/plan/european-ferries/
to get a better idea of what I explained above.
I'd love to hear how you get on