Advice needed. 5 year old trouble!

[LeoTheLion]

Hi, my almost 5 year old son's teacher spoke to me after school about my ds behaviour and lack of concentration. She said he has been on warning every day this week for disrupting class, not listening and being too rough, said dinner ladies have mentioned his name a number of times for being too rough with other kids. I know he isn't the only one who is rough in his class but I don't want him to be that kid who hurts/goes too far.
When it comes to doing writing she said he can start but then trails off and gives up then disrupts class holding others back.
I guess I'm asking if anyone knows how I can calm him down and activities I could do at home to improve writing skills/concentration.

Thanks from a frustrated mum