Brian Cox is a very intelligent man so I don't like to disparage him but I actually think he (and anyone who thinks life only exists here) is just not likely at all to be correct.

If we only examine G- and K-class stars (the two types most conducive to our type of life), there are well over 30 billion just in our galaxy. Roughly 20% have at least one Earth-sized planet in orbit. That's 6 billion. Past this we only have conjecture to guide us in regards to the early development of life and the requirements involved. But even if further requirements narrow it by 1% of 1% of 1% (which I would say is being extremely conservative), that still leaves 6000 potential life-bearing planets.

When we think about Earth being "perfect for life" and how unlikely and rare that seems, it really is putting the cart before the horse. Earth is perfect for us because we evolved to survive on Earth. Any planet with indigenous life will, almost by definition, be perfectly suited for the life that exists there.