I can see no reason why you should mention your period of maternity leave. The simple statement that you were employed by the company for 6 years is completely true (even though you weren't there for one of those years).
Further, whatever the law might say about discrimination, many employers aren't keen to take on women with young families (as they fear that they'll have lots of time off to look after their kids when they're ill, or that they might get pregnant again). So mentioning that you've got a child might go against you (unless, of course, you're applying for a job where childcare skills are important; then it might help you).
However mentioning that you've got the self-confidence to oversee the construction of a house extension would seem to be something that most definitely deserves a place on a c.v.