Can this course be done after 10th?

You may do a diploma in hotel, hospitality, food technology and production, catering, bakery and confectionery etc after 10th. You will then eligible for jobs too. I suggest you to do a 10 +2 and then do a bachelors in any of these diverse courses for higher career prospects.

Yes, you can join IHM Shillong for any Diploma course but you have clear 12th with English and for other information you may visit the institute.