Ford Fiesta Zetec S 2002 - Help with petrol smell please

[JuJo]

Picked up a zetec yesterday for my 17 year old son having just had it MOT'd. It drives very well but the petrol smell is overpowering! I did't notice it until I opened the window whilst driving it home. No obvious petrol leak but main worry is whether safe to drive. Guess wasnt picked up in MOT as didnt have any fuel in tank. He also hates the roaring noise that the powerflow cat back gives out and would like to get rid off this - is it easy or does he have to replace whole exhaust?
Have now found a petrol leak under the back seat!

Edited by JuJo on Wednesday 21st March 21:59