Ofgem estimates that a typical household gas consumption is 12,000kWh a year. Gas used for cooking makes up around 2.5% of the total (300kWh), so that leaves 11,700kWh a year as the typical quantity of gas used for heating and hot water in your home.
From July 2023, the average price cap for gas is £0.08 per kWh, so the annual cost of gas consumption is 11,700 x £0.08 = £936. Sourced here.