A good tutor will write your reference for you amd will give predicted grades. If you have a different tutor for each subject they sgould contact each other to discuss grades, then the referee can enter them on the UCAS application. The info below is pasted from the UCAS website:
If you're applying as an individual
1. Get a reference from a teacher, adviser or professional who knows you
Either ask a tutor, trainer or employer if they'd be happy to do it – if yes, add their email and phone number to the reference page, then click 'Ask referee to complete reference'. First we'll email them with a link and password to the reference page of your application, then we'll ask them to confirm their identity before writing it. (If for any reason they decline we'll let you know.)