Many TV now comes with normal analogue tuners and digital tuners (Freeview).
Analogue will only pick up the "normal" 5 channels (BB1, BBC2, ITV, Four and Five).
Digital will pick up many more (depending where you live in the UK)
Your TV should automatically "tune" the TV to pick up both analogue channels and digital channels.
You may need to use the remote control to switch between watching analogue channels (may be marked as ATV) and your digital channels (may be marked as DTV).
Suggest you read your instruction manual to see how to switch to watch digital TV.
Note analogue signals will soon be switched off in the UK (some places already have) so soon you may only be able to pick up digital channels.