And even if non-business are accepted:-
The telephone �9.99 service has to be taken as well.
FUP - unspecified limits, suspension or disconnection at their say-so.
The OP should compare other ISPs such as Plusnet, IDNet, Newnet, Entanet resellers such as ADSL24, ukfsn and vivaciti, and see what bandwidth is typically provided for �14.99 on a non-LLU service. About 5GB I expect without doing the work myself.
Seems a pretty unsustainable offering.
Tal Talk's Talk3 International seems to be their top offering at �20.49 with a 40GB allowance and totally free phone calls compared to XLN �24.98 with chargeable phone calls. I don't see a BT package at the price mentioned either, nor one with a 10GB allowance. Wonder where the comparison table came from?