Provided you're the policy holder and the lead driver on the rental agreement, any additional drivers are automatically covered as long as they are also listed on the rental agreement.
They must, of course, meet our age requirements and hold a valid internationally recongised driving licence. However, unlike the policy holder, they don't need to be UK residents or hold a UK bank account. This is because in the event that the vehicle is damaged, you are still held responsible for this damage, and you would be expected to pay for the damage. In the event of a claim, we will only reimburse the policy holder, so it's important that it is the policy holder that pays for the damage.