What to do in a day in Dover with a 2-year-old?

Hi !

French (W29) here, i'm thinking of coming to dover for a day only.

Any ideas on what to do with a 2-year-old ? Especially if it rains but also if it doesn't haha.

I want to have an english breakfast maybe at brenda's kitchen ans also go to a bookshop.

Also we'll be walking from the ferry so it can't be too far from the port

Thanks !