They want you to pay 7,5 euros just to climb a small tower. You don't have an option to just quickly access the castle.It's better to explore the castlegardens, it's really beautiful and not crowded.
In the chapel there is a guy who can calligraph your name on a bookmark - looks amazing! He knows a lot about chapel too and is very talkative-just ask :)Don't miss virtual castle - dragon story rocks