I have flown quite a few times to Rotterdam.
Cessna 150 Tailwheel.
I have found Zestinhoven (Rotterdam) ATC very helpfull.
The flight is quite simple - if you want a copy of the plog I use send me an e.mail I will copy it to you. basically it's simply
Dover - Koksyde (KOK VOR)- Oostende - COA (called Costa)- HND - RTD.
or simpler - set yr VOR to RTD 090 - follow the coast till the nedle centers - turn right.
Couple of things - contact Rotterdam latest at Middenzeeland - ask for progressive taxi - there are bloody lines everywhere - they usually park you behind the hangers - most of the little parking spaces near the fence are taken by - club flyers - so dont park there someone will want you to move.
ASK FOR STARTUP - they get irrate if you just start.
Fuel when you land - you can lose an hour if you leave it till you go.
cost of fuel - about the same as everywhere.
Note : I see someone said Middenzeeland is another option - be carefull - customs is now only available there with 24 hrs notice (since about Jan. This year.)
last thing Rotterdam is below sea level.
Its a great place to visit. buses to town and easy flight - if you dont mind water.