UK Law and building regulations state that anything that is to be installed permanently outside and, in a pond, should be hard wired into the electrical circuit. This means that pumps and filters do not come with plugs fitted!
There is a small part of these regulations (part P), that means an electrical circuit can be installed as a DIY job if it is not permanently wired into the mains. This can be done by using a plug into an RCD plugged into an indoor socket.
Legally we can not give specific electrical advice, but you may find the following information useful when considering your pond set up.
The image below shows how an electrical supply could be taken into a garden using a Circuit Breaker which is plugged into an indoor socket and then run through the house wall to the outside. A circuit breaker will prevent your house electrics tripping should there be any electrical problems with your equipment at any point and we highly recommend using one. It is then connected to armoured cable (cable with a protective casing in case it is dug into when buried in the ground), which is run through the garden until it reaches the location of the switchbox. As you will see in the diagram, red and white tape has been placed on top of the cable when it is underground. This is a useful tip to help you locate the cable once it is buried, to avoid accidently digging it up. The armoured cable is then adapted back to the standard cable above ground and connected into the switch box.
The pond equipment is then hard wired into the outlets on the switch box. The pond equipment can now be switched on and off outside without having to disconnect from the mains.
We are unable to give specific electrical advice in our sales centre because we are not trained in this area, so if you do have a question we would recommend speaking to a qualified electrician.
If you'd like to read more information on wattage and calculating the cost of running equipment then you may find this blog useful: Pond Electrics