That depends how able you are with a screwdriver & a pair of wire strippers. You can fit sockets using a mains kit from somewhere like Towsure. Put the wires inside the lockers & under the floor so you can have outlets where you want. If this is too much beyond your limits, get a camping EHU. If you shop around you can find them for around £30. DO NOT buy anything like this from eBay. They have no protection in the wet or in the event of cut wires, & are potentially lethal. As they always say, if in doubt contact a qualified electrician.
The 'camping EHU' link in steves post is what i have in my FC, no installation required. I have cut the wire and put a socket under the camper and connect it this way, just to save feeding the cable under the canvas, however you could just buy the unit, feed the cable through/under the canvas and plug it in, no wiring involved.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.