Definitely not a tv issue.
Virgin TV picture is terrible. Even the little channel icons in the corner of the screen are hard to read. Bought a new tv for this crap. Everything seems set up correctly. I have seen mention of a possible upstream issue on other posts?
Mines a few weeks old now, but for me the picture is great on the HD channels. Unfortunately non hd is a lucky dip, which seems to all providers.
What tv did you buy, 4k? If you are watching SD channels on a large 4k TV it will be rubbish. I never watch sd, I watch HD channels only.