We found prices in general in Netherland, Luxembourg, Germany, France & Switzerland all very expensive compared to previous years.
You expect a change due to the Pound/Euro rate - but internal pricing in these countries has also shot up.
Luxembourg & Switzerland still have cheaper fuel in their favour - but the Netherlands is now about 1.40+ Euro's per litre

for petrol - so if your arriving via Ijmuiden then have your tank reasonably full.
Not sure how Eastern Europe will be now - we were in Czeck Rep. & Slovakia last year & it was still good value - as long as your not trying to stay/eat/drink in the tourist spots where the price benefits all but disappear?
Cheers.......................Grizzly