I would like to draw attention to the DANGERS of using socket covers.
Since the 1940's the 13A power sockets used in the UK have had to incorporate a shutter mechanism which prevents anything but a power plug being inserted into them, thus little fingers cannot touch anything dangerous. Socket covers will fit into a socket because they are designed to be the same shape as a power plug, however small differences in their design mean that it is possible to insert them upside down into the earth socket only, this disables the safety mechanism and renders the socket dangerous.
See www.fatallyflawed.org.uk for more information.
I write as a qualified electrical engineer and fellow of the Institution of Engineering and Technology, the professional body for UK engineers.