Public torrent sites are notorious for "fake" files that are actually executables designed to infect your computer.
If you are abroad, the most "official" way to watch is by using a VPN with a UK server. This allows you to access ITVX for free (with ads) or via a premium subscription. im a celebrity get me out of here uk torrent
Private or semi-private trackers dedicated to UK television (like TVVault) are the "holy grail" for high-bitrate 1080p copies and complete box sets of past seasons. Public torrent sites are notorious for "fake" files