I went into a pound shop to get a couple of TV aerial cables tonight (long boring story) and was somewhat surprised to find that I could buy either a 5 metre cable, or a 1.5 metre cable plus a surge suppressor plug adaptor - which has a 13A plug and socket, and antenna in and out sockets. So since 1.5 metre was more than long enough I got the ones with surge suppressors, of course, and have put one on the big TV, the other on the computer I use with it. I'm not sure that they'll be up to much at that price, but since I don't have a surge suppressor in that room (which is something I need to rectify) they'll do for now. I don't think they'll do any harm, anyway.
So if you need a cable or a cheapo surge suppressor pound shops may be worth a look - incidentally, as well as the ones I got, they also have a type with a phone line in and out instead of TV antenna.