Hello Alan C, the sockets are of the two pin variety, on a block of between 4 and 8 sockets.
I have used Houx many times recently, and take the following kit.

As you can see in the above piccie, the orange lead is the cable with the standard exterior round sockets (one male, one female). You then need a two pin plug with female round socket as seen towards the top of the picture. This is what plugs into the hook-up. And we then use a male round socket to standard UK three pin plug socket into which we plug an RCD. These can be seen at the bottom of the pic. We then plug 4-way extension leads into this.
Please note, that because it is outdoors, I would strongly suggest that you buy a proper extension lead from either a camping outlet or a boating chandlers, for the sake of a bit of safety it is worth the extra cost. You will also need the right kind of adaptor. We then add the gardening type trip breakers at the tent end before plugging in the UK 4-way gang-sockets.
Hope that helps.