You need to contact your current provider in order to close your account in the event that you are moving out of the property so that they can arrange for your final invoices.
If you are changing electricity or gas retailer at your existing address, in most cases closure will happen automatically however you can still let your provider know to close your accounts.
For broadband, it is best to contact your provider to close your account in the even of a move out or transfer of provider scenario.