You'll be able to choose any of the fixed line providers.
How you 'allocate' across your house will depend on the size of the house and the needs of those in your household.
The fibre will be run to a small terminal box within the home, your chosen provider's modem/router will be connected to this. You may get a choice of where the terminal box is located within reason, but a mains socket will be required close by to power it (installers will not install new mains circuit or sockets for you, so get that done in advance if required)
In many cases, the wifi signal might be strong enough throughout the house for your needs but it not, you can do one or more of add repeaters or mains network extenders, replace the provider wifi with a mesh network, or add a switch to the router and hard wire to different areas of your home where you want best performance.