On 20 March 2020 Ofcom will launch the broadband universal service obligation to be delivered by BT and KCOM. Further details are available here:
If you already have a voucher issued, your supplier must complete your installation by 31 December 2019.
This is how the scheme works for people with vouchers:
Scheme terms and conditions for beneficiaries: https://basicbroadband.culture.gov.uk/wp-content/uploads/2019/01/Better-Broadband-Voucher-Scheme-Beneficiary-TsCs-1.0.pdf