Santa got me a pioneer TF100.

I've currently got it connected to a little tv top aerial  and get a few chan's but none of the standard ones (BBC1,2,ITV,C4,C5). I've connected it to the roof top aerial and can get all chan's through that.

So..........

How do I go about taking a second feed from the rooftop aerial? Is it possible? Is it easy? Will it effect quality?

Cheers

MO