The easiest thing to do would be to move your current package to your new house with the missus. This way you will keep the same email addresses/ webspace etc. If your lady wants TV and phone as well, express and interest and see what deals you can get
Then, when you have moved out (or just before) get your mum to phone ntl and order BB or whatever she wants for her house and she will have a new modem installed and register her own email addresses / webspace etc.