One of the ideas of getting to Germany is to go through Ireland.
To get to the ferry from the Airport:
[http://www.tripadvisor.com/ShowTopic-g186605-i90-k2831603-Ferry_to_airpo...
Basically bus service for about £6.
With a Eurail Pass the Ferry is discounted by 30%. A cabin is additional cost.
There are two points of ferry departure from Ireland:
Dublin and Rosslare
Dublin goes to Hollyhead in Northern England, and takes about 2 hours. Rosslare goes to Pembroke in Wales. The current fare is £31 one-way.
There is also a ferry to either Roscoff or Cherbourg in France. It is an overnight trip (about 19-20 hours).
Other detail is provided here: [http://www.eurail.com/trains-europe/ferries/irish-ferries#additional-inf...
If going through London, the Eurostar train is not included but also has a discount fair for Eurail passholders. The trip to Paris is 2h 15m.
Now the Eurail Pass starts to work.
From Paris the high speed train goes to Frankfurt in 3h 50m. (Recommended to make reservations).
The train from Frankfurt to Heidelburg runs every hour takes about 1h, trains run from 6am to 12 am.
