Year 7 homework doesn't tend to be long pieces so get in the habit of them doing it when it's set so they don't get behind. It also means that if a problem comes to light there is time to sort it out.
I would always start by helping them plan their homework and checking its done and taken for the day its to be handed in. Note- some teachers may ask for it to be handed in other than in a lesson. This may be to their pigeon hole in the department office for example.
Most staff will respond to an email if a pupil has a real problem with homework especially at the beginning of term - as long as they don't make a habit of just not listening!! This should be from the pupil not the parent unless there is a more general concern. But if time allows its better to try to find the teacher during the next day.
Thanks KB. I've been making him get into the habit of doing the homework the night it is set. I'm glad you said about the taking it in on a different day. I'll need to double check when he needs things. I've been checking his bag each day just to make sure he's got everything he needs as that's a skill it's going to take him a little while to brush up on