unit costs

how much does 1 unit on my meter cost if my meter measures in cubic feet and the current gas unit rate is 2.5p?

Assuming your meter looks like this -

and you’re ignoring the red section,
a unit is 100 cu ft = 2·83 cu metres
Allowing for slight variation in the current calorific value, this equates to about 32 kWh × 2·5p = 80p

@mouse_1 - to convert between a gas volume and kWh there is a handy calculator here: https://www.businessenergy.com/gas/kwh-calculator.html