You will be billed every quarter for all the electricity and any gas you have used in the business.
Until you've been trading for a few months you won't know exactly how much energy the business will use. Your energy supplier may be able to give you some guidance, based on the size of your premises and on the nature of the equipment you will use, such as chiller cabinets and refrigerated serve-over counters. You can adjust the figures once you have been in the premises for a few months to make your financial forecast more accurate.
It's worth shopping around the different energy companies to get the best deal for your business, particularly if you're going to be a heavy energy user.
Energy prices are high and seem very likely to keep on rising in future, so it makes good sense to include efficiency measures when you fit out and equip your premises. Things to consider include low energy lighting and energy-efficient equipment, particularly fridges and freezers which are on all the time.