First things first, you will need to file a flight plan showing where you intend to cross from one country to another, detailing the time you anticipate being overhead.
Within Germany you will not need to file a flight plan but anytime you cross a country's border, you will need to do so. The big difference is if you (eg) cross from Belgium to Germany, you are going from one Shengen - member country to another so passport checks are not required - they will be required when going from (eg) UK - which is non Shengen - to most other european countries.
Therefore I would recommend you fly from the UK into a larger airport - for example Ostend in Belgium, Rotterdam in Holland - where you can clear customs. From there onwards just file your flight plan, there is no need to worry about customs from Shengen countries. Otherwise, ring your destination airport and ask about getting border clearance. Last week I flew back from the UK via Middenzee (EHMZ) and they organised everything for me so I can also recommend going there.
A few things to note about Germany:
1) German FIS will always provide traffic information if you want it - at least I've never been refused. There are three main FIS areas - Bremen Information, Langen Information and Munich Information so once you cross into Germany (or leave the circuit if flying from place to place in Germany), call them, they are very helpful.
2) The AIPs for Germany are not openly available, they need to be purchased although some airfield post some on their website. Beware of not having them - some airfields - Bonn Hangelaar springs to mind - have a very tight circuit for noise abatement rules and look to penalise infringers.
However there is a "get out of jail card" for anyone who infringes..... ;-)
3) If you're thinking of doing a lot of hops and jumps between airfields within Germany, consider buying the "Landegutscheinheft", which is now available for a reduced fee.
There are two books, north and south, which offer 3 free landings at selected airfields within German - if you google "Landegutscheinheft" you will see the airfields. I think they now cost around €40 for both and the savings for landing fees is immense. However you need to check if our destination airfield is a member of this scheme.
4) Have fun, it's not as difficult as many would have you think.
Last edited by Steve6443; 3rd Aug 2013 at 11:51.