Three ways to get tv pic to your set: ariel, cable tv or satelite.
Since you have cable you need to go to Freeview via ariel if taking cable out.
If you want HD channels these are available on freeview.
There are two types of freeview tuner, HD and regular.
You either need to buy a set with freeview HD tuner, or buy a cheeper telly and buy a separate freeviewd HD box (either with or without recorder built in).
As for on demand iplayer etc….again you can either get this built into tv (we have a 32 inch samsung thats rather nice and has HD and internet) or yo u can get dvd players and settop boxes from sony, samsung and others that have a mix of features.
As for tv licence, just ignore the letters, don’t think they are very persistent …..are they 😈