KatyM: I think that you would be perfectly in order to tell her that. After all, she is asking you to look after her LO because you are a (superb) childminder! She would not be asking you if you were an accountant, iyswim.
Pinkchick: it is very likely that your contract states that notice period does not include time off. Check your contract. If you use the NCMA ones and have not amended that section on the back of the contract (the teeny tiny grey writing!) then the notice period does not include time off.
Let's hope my ex-mum delivers her cheque to me today. I had said in the letter of demand I would issue summons in the small claims court on 12 Dec if I had not received payment. The ridiculous thing is that I do not have the money to summons her right now!!!