You need a TV license if you plan on watching live feeds of TV programs - read about it on the
TV license website and
this Guardian article.
If you don't watch anything live, and just watch on Catch-up, you don't need a license. You don't need a license to watch DVDs or use online services like Netflix.
I would let them know you don't need a license
using this form, otherwise you'll likely get letters telling you that you need one.