UK maternity law?

I go on this parenting messageboard and a woman who had her baby end of last year has just posted saying she doesn't want to go back to work and so has planned to get pregnant again and have babies back to back for the next few years so she is on maternity leave and getting maternity pay from her employer for virtually the entire time - and says that the bit of time she wouldn't be covered by maternity leave she'll take her annual holiday allowance in anyway. I won't go into what I think of people lilke this - other than to say that I think this is a despicable reason to have kids, just because you can't be bothered to work, people like that don't deserve such a blessing, so please don't think I'm asking this about myself! I'm just wondering out of curiousity, would she actually get away with this indefinitely? - claiming money off her employer without having to work hardly any time at all because she keeps having babies? Or would he have grounds to fire her eventually? (In the UK)