Essentially, the person controlling a drone is fully responsible for the safe operation of any flight, but it is important to consider whether a permission (not a licence) from the CAA is needed.
You must request permission from the CAA if you plan to:
fly the a drone on a commercial basis (i.e. conducting ‘aerial work’) or
fly a camera/surveillance fitted drone within congested areas or closer (than the distances listed within Article 167) to people or properties (vehicles, vessels or structures) that are not under your control
Permission is not required if:
the drone will not be flown close to people or properties, and you will not get ‘valuable consideration’ (i.e. payment) from the flight, then a permission is not needed;
Permission is also not required for ‘practice’ or demonstration flights. However, the other requirements of Articles 166 and 167 must still be complied with, and it must also be ensured that no one is endangered while flying the aircraft.
The regulations are intended to protect people and / or properties that are not involved in the activity. They are also aimed at being as ‘light touch’ and proportionate as possible, so there is a great deal that can be done (especially for private or recreational flights) without the need to approach the CAA at all.
Link below to CAA approved operators.