If you are one of the small number still on ADSL (so served from the exchange rather than FTTC served from a cabinet ) , the product you presumably are on is an upto 24Mb one (I can’t recall it’s product name , obviously it doesn’t include the word ‘fibre’) , was marketed as 17Mb and , you state you get around 5Mb, so I’d estimate that puts you 4-5Km from the exchange…it’s very rare to not have been offered an FTTC upgrade path in the past .
TBH , your change to FTTP would need to be checked with BT , as far as I know the basic FTTP profile is 40Mb (sold as BT Essential, not to be confused with Home Essentials the social tariff) so I’d suspect you will be moved onto that , but as an ADSL customer not FTTC /VDSL there is no directly comparable FTTP equivalent , if it happens to be F1 you get ( re reading your original post that may be the case ) , unlike most , I suspect you will see a price increase unless your ADSL price were more than the current F1 price , but I’d struggle to see how this can be achieved without some contractual tie up , as you , unlike FTTC to FTTP migrations are not simply changing the transmission medium .
