Andreas, get in touch with SRS (Chris is the man to contact), they do post to Europe, other members of Pentax Forums - Pentax User Photography Forums from various countries have had items delivered
would add Mifsuds to the two listed above - had excellent customer service from them. They parcel up well and post quickly and often have good prices. Their website isnt the best but they are very quick to answer email - useful for overseas purchases I find
SRS is often my first port of call for Pentax, great stock even on obscure stuff and generally great prices, but not always convinced about the standard of their packing (my K10D body in its Pentax box was put straight in a Citilink plastic bag, no padding) and CityLink are a bit rubbish at delivery round here
Tried to use Park on couple of occasions as they have good reputation, but their web site doesnt show stock levels (or it didnt last time I looked) and I have been caught out waiting for dispatch/delivery when they dont have it in stock and didnt let me know - though they were always helpful when I phoned
If you are feeling flush, Robert White stock some lovely things that will be a bargain at 1 Pount = 1 Euro
I recently bought at three UK dealers via the internet and all of them were very friendly and helpful and did everything to get the order over to Germany asap:
Warehouse Express - Digital Camera, Digital SLR Cameras, Lens, Canon, Nikon - Discounter with everything photographic. Sometimes their workflow can be a bit sloppy, but the people are really nice and helpful. Shipping to Germany was extraordinarily fast and (considering I got two large packages, weighing in at about 25-30 kgs) cheap.
I bought a lot of filters (HiTech mainly) from both specialist dealers and can recommend them without reservation. Even warehouseexpress, despite being a big discount store, is really a good address.
Additionally I bought from MXV Photographic recently (a Bigma) and they very nice, too and fast delivering the lens. But postage was on the high side, though within Royal Mail (they are expensive!) limits.
In the past I bought a lot from the usual suspects, when I was in the country: jessops, mainly. But the quality of service is very dependend on the people in the store and varies widely. Nevertheless they always offered excellent after sales services, when I had a problem with a product.
Just too advantage of today's Euro-versus-Pound ration and bought a refurbished Pentax 16-50 off the Warehouseexpress website - a mere 320 Pounds + postage, which translates into 362 Euros - a real bargain, considering it is around 600 Euros new over here.