Can you ask an employer, private tutor or one of the teachers from your high school to do a UCAS reference for you?
You can, but this is normally prearranged with the University and the application going through UCAS is just to comply with the University's contract with UCAS that all undergraduates will go via that process
But if you are only a year out of school, try asking someone there, such as the Sixth Form administrator in the first place. Be aware, though, that some schools may charge a fee for this.
Is a reference essential on a UCAS application? I left high school last year and so I have no clue who to ask to be my reference. I am contemplating submitting without a reference.
Its better & easier to get a reference, im sure your school tutor will happily act as your referee, normally people are happy to do this sort of thing.