Work in School - should I work my contract?

FBaby

 I don't want to spend a minute longer anywhere else in an environment where I could inadvertently touch something that has been used by someone -asymptomatic, for example.

I don't understand this. Surely you are at risk when you are around people. If all you're doing is paperwork at a desk (that you can wipe down), or preparing the room for the following day, taking stock of what might need reordering etc...how is that really putting you at risk?

You want to go home early, we get it but then ask to amend your hours accordingly temporarily and don't get paid for it.