Get a cooler and keep drinks and snacks on ice. We usually carry lunch meats, bread, mustard, mayo and etc for sandwiches. When we are camping, we will also have each meal planned ahead and will bring along sausage and eggs and boxed mac&cheese and etc.
1800 miles is probably at least 3 days on the road so plan your overnights for inexpensive places to rest. If you have kids on the trip, you may want to look ahead for inexpensive places to stop and distract them and let them get some exercise. When our kids were young, we would stop at McDonalds because they had indoor playgrounds for them to climb on and run about it. We could order a $1 ice cream or drink for each or to share and get a reasonable break from the driving. Entertain kids with games that work in the car - spotting license plates from other states,countries etc, making words from the letters on license plates, 20 questions, I-Spy, and stuff. We have a DVD player in the car and let them watch movies that I pick up at thrift stores for cheap for weeks/months ahead and store up or we rent them for $1 at RedBox along the way.
Plan ahead looking at toll-ways vs. other roads and determine what is the most efficient map for your needs. I don't know about EU driving but in the US North East you can spend a lot of money on tolls. In some cases there can be affordable alternatives, but these are usually going to be slower.
Do not drive past your wakefulness!!! It is not worth the risk. If you are tired or nodding off, pull off, and either sleep in your car or pay lots of money for a crappy motel room and sleep.
Best wishes, Ap.