Being able to dress themselves to a certain level is sueful. They will be doing PE, so make sure he can sort out his main items of clothing. As for shoes - go for velco!
Toileting will be done by your little one alone, no help usually. So let him practise from now. I know it takes longer, but he needs to have a go. Same as knowing to flush and then wash hands afterwards.
Being able to eat his dinner with cutlery, reeasonably tidy, especially if staying for school dinners.
If he goes to nursery he may do some of these there anyway. I know DD does a lot of these things at nursery (she also starts in September) - they just give them more time.
They could probably do with being able to recognise their own naame written down. Ability to write name is handy, but reading/writing will be covered from scratch in reception anyway.
Educationally isn't so much of a big thing as they will do baseline assessments within a few weeks of starting and the teacher will work out what each child needs to learn and at what point they need to start from.
So rather than specifics there - look more for being able to sit still and listen, to remain focuses on a ask for a lengthy period of time, sharing, listening to others, hand up to ask questions, waiting turn...again lots of this I bet he is doing at nursery anyway.
The main thing to remember is that the children are all at completely different levels both educationally and emotionally when they start. Some will be ahead in certain areas; some behind in areas. The teachers will be completely used to this and lessons will be geared towards it.