Cerberus standard FTTP prices are at https://www.cerberusnetworks.co.uk/connectivity-broa...
Unfortunately, last I heard, there is no "working line takeover" process for FTTP. (EDIT: Someone please correct me if this is wrong, but Google doesn't seem to show any news on this topic)
If you have a workable backup connection (e.g. FTTC or 4G) that will keep you going for a few weeks then you could just cease the old service and order new. There are some companies that will sell you FTTC on 1-month contract.
Otherwise, if you don't want to lose service: place the new order now with the new ISP, and keep the old service running. Openreach will most likely install a second ONT in your property (pulling a second fibre in), or possibly swap your ONT for a four-port one. When the new service is live, then cancel the old one. You will end up paying for service during the overlap, and of course you have the hassle of having another engineer visit, more drilling etc - unless you already have an older installation with 4-port ONT and/or a 4-strand fibre from external CSP.
Edited by candlerb (Tue 04-Feb-20 12:31:47)