Hi Brenda and welcome to SM Network.
Good for you! Even if this is your last school musical you can always get back onstage later through community groups and it sounds like your teachers really need you as an SM. You will find heaps of info on this site - try using the search function for specific questions - but you will also be able to get plenty of help from the network as you work out what your detailed questions are. Its a bit hard for us to give general tips because stage management covers so many different areas
However its a good idea to get as familiar as you can with the script and the score as soon as you recieve it, and there is plenty you can do to prepare paperwork etc in advance. I am sure there are some threads on 'pre-production' requirements somewhere on the boards and there are LOTS of great templates for just about everything in the examples of paperwork board.
Also maybe some people who have done Grease will have some specific ideas relating to tricky costume changes, props etc.
Have a great break and enjoy the show from a different angle - even if you return to acting as preference this will help you be a better actor as you will understand more about the process of creating theatre. Congrats on being someone your teacher can rely on!
Cheers
ChaCha