Yes Nicola. It is indeed possible to watch TV on your computer. You will need what is called a TV card. You can buy one from almost any PC shop including PC world. There are many available with a variety of features such as capturing etc. They start from around �30-35 i think. You then need to fit the card into the pc as per the instructions, or get someone who knows there way around pc's to fit it for you. Then simply plug an aerial into the aerial connection on the back of the card, tune in the channels in the tv software, as you would a normal tv, and away you go!
Have fun. Mark :-)