Electrical switched cable outlet plate

Appropriate idea - but you can get one in white plastic for less than a fiver. Do you have a Screwfix or B&Q nearby?

That's what you want, a "switched spur with flex outlet", but don't pay that kind of price for something that'll be hidden from view. Many of them can have the cable coming out of the side rather than the front (you may have to file a bit out of the plate and/or wall), which reduces the required depth even more. See, for example,

If it's behind the freezer do you really want an expensive chrome one? There are plastic ones available where the cord outlet is to the side rather than front therefore saving more depth. Here's one example:-

Go to your local shed/B&Q/Wickes/whathaveyou and look for a plain white unit. Pick one with a knock out on the bottom - a cable sticking straight out from the plate probably isn't going to make a good replacement for a plug & socket combination.

/jk

I got one cheers