Moving to a new house and it can access 'Ultrafast Fibre' (it has not been installed in this house before though).
Does the price quoted for 'Ultrafast Fibre 100' at £39.99 include line rental?
Great! So £39.99 is the main base cost (minus telephone charges?)
Will the new FTTP line allow me to make phone calls also? i.e. I will be assigned a new phone number / take over the existing phone number?
You will be able to make calls, usually by Fibre Voice Access, or any existing copper infrastructure.
If you have an existing copper connection as well as FTTP, and are still connected to the same physical exchange, then you would be able to keep your number. Otherwise you will be given a new number, with the option of a 30 day changed number announcement on your old number.