If you do switch to an energy supplier that goes out of business, you will be protected by the energy regulator Ofgem.
If there is no takeover of your energy company, Ofgem will move you to a new supplier known as a Supplier of Last Resort to ensure your energy supply continues. Any credit balance you have will also be protected during this process.
As you will be on a ‘deemed’ contract with your new supplier your rates may be higher. However, you can switch to a supplier of your choice at any time with no exit fees payable.