London overground question

[Daisykath]

This may be dumb - does a ticket need to be used at a certain time or is it like underground? As in, I’m buying a Smalltown - London ticket and the first section of travel on the train obviously has to be at a certain time, but it then says 12.00 for an overground section of travel. I’m wondering if we can stop for lunch before getting the overground or if time makes a difference. If that makes any sense, please do help! Thanks 🙏🏼

Is it an open ticket? Or fixed?

The train bit is not an open ticket but I think the tube and overground bit is an anytime ticket, having gone further down the booking process. So I think I’ve answered my own question, thank you.