so if a tv pixalates, does that mean its on it's way out or can it also mean the Arial is on its way out
Yes, it could mean an issue with the aerial. But you can eliminate that by testing both tv's separately. If one tv pixelates but the other doesnt when connected separately to the aerial, it's the tv at fault. If both tv's pixelated when connected separately to the aerial, then it is fair to say the aerial would likely be at fault.
I used this method to determine my Sky HD box with twin aerial feeds was not faulty and instead, it was the dish \ LNB combination.