As I am 1 mile (exactly) from the cabinet what speed are we likely to be offered?
Fibre doesn't depend on distance (*), only what type of optical line termination equipment Openreach have. Most likely you will be able to get speeds up to 330/50 or 330/30. There will be slower packages like 160/30, 200/20, 80/20.
(*) To be more accurate, it only works up to a certain distance e.g. 20km. But as long as you are within optical range, you will get the full speed regardless of the actual distance.
will I need to change the provider? I currently have two lines - one AAISP(btw) and other Pulse8(TTB).
Not many service providers currently offer FTTP, see https://www.thinkbroadband.com/packages/fttp-broadband
AAISP have recently started offering FTTP, and are limiting speeds to 160/30 for now. See: https://www.ispreview.co.uk/index.php/2018/07/uk-isp...
Prices will go up sharply when they turn this on I assume?
Not necessarily. Firstly, you are not forced to migrate - you can stay on FTTC as long as you like. Secondly, the price will depend on the service you take. If you take a 80/20 service over FTTP, the cost will be broadly in line with 80/20 FTTC - except that you will get the full speed as if you were right next to the cabinet. With AAISP you should end up paying the same for FTTP 80/20 as FTTC. If you want 160/30 service then I think it's an extra £10/month.
AAISP normally has a £100 setup and 12 month contract for a new FTTP service, but I don't know what they'll charge for a regrade of existing customer.
Note: if you want *two* separate FTTP services, I don't know how this will be delivered. OR used to install a multi-port ONT, but not any more. Maybe you'll end up with two separate ONTs and fibres.