Clinging at drop-off doesn't mean he's not ready for school
Clinginess before starting school is one of the normal peaks of separation anxiety, it is not a verdict on whether your child is ready. What helps most is a goodbye that is brief, warm, and exactly the same every time; children pick up confidence from the ritual, not from how long you linger.
If your child is holding onto your leg every morning this term, that doesn't mean he isn't ready for school. It's separation anxiety doing what it normally does around big transitions, not a verdict on him, or on you. The part that actually helps isn't a longer goodbye. It's a short one that looks the same every time.
What's really happening
It makes sense this has been eating up your summer. Starting school is a big change, and clinginess right now doesn't mean he's behind. Separation anxiety naturally rises at a few predictable points, around 18 months, again around age 3, and again at school entry, and each time, it's a sign that attachment is working the way it's supposed to, not a sign that something's wrong.
At the door, he's reading your face and your pause for the answer to one question: is this safe? That's why both ends of the spectrum can make the next goodbye harder, lingering too long, and slipping out without saying anything at all. Neither is a mistake exactly. They're just two ways of leaving the question open, when what he needs is a clear answer, given the same way each time.
Tonight you can
Build one short goodbye ritual and practise it before the school run actually needs it. Same words, same hug, same order, tonight, at bedtime, or on the walk to the shop. The ritual doesn't have to be big. It has to be repeatable.
Leave once, warmly, and then leave. Don't go back in for one more hug, even when he asks, especially when he asks. Going back teaches that the goodbye was negotiable, which means tomorrow's goodbye has to be renegotiated too. One warm exit, held to, is what lets the ritual do its job.
Name the reunion before you go. Something as plain as "after lunch, I come back" gives the story an ending he can hold onto while you're gone, instead of a gap he has to fill in himself.
What not to worry about
Clinging at the school door is developmentally on time. It says he's attached, and that he's reading the moment correctly, not that he's behind, and not that school is going to go badly for him. This is one of the ordinary peaks, not a sign you've missed something or that he needs more preparation than he's had.
When to seek help
If separation distress stays extreme for weeks after he's had time to settle in, and it's stopping him from functioning at school, that's the point to bring in the school and a professional. It's persistence that matters here, not the first hard mornings, those are expected, and they pass on their own for most children.