When you say copper broadband , is that exchange based ADSL , or was/is FTTC available but you don’t have it , or because of the distance from the cabinet, the speed would be no better than ADSL or potentially worse ?
As already said, if you are prepared to pay for the construction, then FTTPod may be an option, but BT Consumer don’t offer that Openreach product, you would have to approach an ISP that does, the initial desk top survey is ‘free’ to get a ballpark figure of what you would be expected to pay, if you decide to proceed further, you pay a non returnable fee (around £300 ) this gets a bespoke contractual price, if you still wish to proceed, you pay whatever ISP you approached the full amount, minus the £300, and OR begin the construction, the point ( in a way ) is if there is FTTP relatively close by, the the aggregation node may also be near by , and the costs may be low ( low still being in the thousands as opposed to the 10’s of thousands).
Obviously if the wholesale checker doesn’t show FTTPod as available this avenue isn’t available.
FWIW, if a developer asks for FTTP , then when OR plan the work, they don’t necessarily pick up any close by property’s and include them in the scheme, so it’s unlikely that FTTP will just appear as available because of the proximity of this development.
Another possibility is if your current service is below the Universal Service Obligation (USO) of 10Mb, you could ask for a USO compliant connection, but if mobile broadband is capable of 10Mb you wouldn’t qualify
