I visited this WHS in June 2016. I visited the palace and vast gardens in the afternoon just before the Nocturne festival took place (starring Elton John). As it was raining when I arrived I decided to buy the very expensive ticket to visit the palace interior and the gardens. The palace interior though is more like a wealthy mansion's interior and does not compare to other palaces on the WH list. The main focus is Winston Churchill and unless you're a movie set fan or keen to learn more on Churchill you wouldn't be missing much if you skipped the palace interior. The highlight for me was the recently restored North Portico just above the main entrance and you don't need to pay extra to see that. I also loved the old palace key displayed near the entrance. Luckily the sun came out while I was visiting the palace so I gladly went outdoors to explore the water gardens (picture), the private Italian garden, the lakeside trail and the far away pleasure gardens. If you park your car at the car park closest to the pleasure gardens trail and you want to have a look at the gift shop, head to the gift shop first. That way you'll be able to visit the pleasure gardens and then head towards the car park without having to go all the way back to the palace. Make sure to allow at least a full day to visit the lovely old colleges, churches and university town of Oxford even though it isn't a WHS (yet).