Adding first fish tomorrow

[Lavey29]

There is nothing in the tank apart from rock/sand and water. Do I still need to quarantine?.

Yes, clowns especially should be in QT with copper and prazi at least. If they bring disease into your tank not only will they probably not survive but you can't add anything else for 76 days either. I went through this when my tank was new and did not QT the clowns. Check your LFS and see if they QT maybe for an extra fee so you don't have bad issues with a new set up. It is sad to see fish get sick and suffer.