You will be billed every quarter for all the electricity and any gas you have used in the business.
Until you have been trading for a few months you will not 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 the nature of any equipment you will be using. (It is likely that you will need a three-phase electricity supply if you use equipment such as vehicle lifts.) You can adjust the figures once you have been in the premises for a few months.
Energy prices are high and seem likely to keep on rising in future, so it makes good sense to include efficiency measures when you fit out and equip your premises. Large buildings like industrial units can be difficult and expensive to heat, so think about which parts of your premises need to be warm and which parts can remain unheated.
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.