1)I had a very good holiday. I ate a lot of ice-cream during my summer holidays. I finished my homework late because I’m a lazy guy.
2)I enjoyed myself during the holidays. Could you say: I enjoyed my holiday though it went by very quickly? <~~yes
3)I took part in the school's world volleyball competition. We had to speak only English to make ourselves understood. I met new people.
4)We came in third.
5)I helped my mum in the shop and my father on the farm.
6)I spent my holidays in a children's hospital where I was treated for anorexia.
7)Doctors rarely let my see my parents. I couldn't see my friends or phone them.
8)When I was discharged from hospital, the doctor congratulated me warmly. Now that I'm back to school I'll have to make up for the lost time.
Read carefully to compare your sentences with my revisions. Watch for large and small things -- word choice, punctuation, spaces after commas and periods, etc.