Not only don't I know how to use it, I really don't know what it does.
Sounds like a set-top box with twin tuner to receive, and hard drive to record, digital terrestrial TV transmissions. If it's not been used for some time, then it may need a retune. During your UK absence, DTV has been gradually phased in across the UK regions (still in progress) and periodic retunes have been required. If the TV is only showing 5 stations it sounds as if you are still watching analogue TV via its own tuner, rather than digital TV (Freeview) from the Thompson STB. Depending on how the two are connected, you could try selecting an AV input on the TV.
A restless noisy hard drive seems to be a feature of some, but not all, such devices.