As others have indicated, there are generally no restrictions upon taking photographs when you're on your own land, in a public place or where you've been given permission to take photographs. (There are, of course, certain exceptions that apply to everything from secret military installations to voyeurism or CCTV but they're simply not relevant here).
Even if you take photographs in private places then (as long as you steer clear of the various types of exceptions that I've alluded to above) you're still not committing a criminal offence. It's entirely a civil matter. For example, as far as the criminal law is concerned, it's perfectly legal to walk into someone's garden to photograph them there (or, through the windows of their house) inside their homes.
The person who takes a photograph (or the organisation that he/she is working for when doing so) is the copyright holder and is free to publish it wherever he/she (or other copyright holder) likes. If the publication is for commercial gain (e.g. a photograph of someone enjoying a pint of beer used in order to promote that brand of beer), a person in a photograph can demand (and, if necessary, sue for) a modelling fee but, in general, people photographed in public places have no say about the publication of their images. The rules (or lack of them) are exactly the same for photographs of children as they are for those of adults.