I've been in touch with the garage who sold me the car and they're going to pay for me to have the seal replaced. As they're in Manchester and I'm in Newcastle they've asked me to take it to a local garage and get a quote for the job.
My local garage is booked for the next month, so the seller of the car has said to take it to any local one. I don't really trust garages as I've had bad experiences with them in the past. I was recommended this one by my mechanic mate who sends work to him, as my mate is mobile and not garaged. He could do the job but it needs to be on a lift or over a pit.
Normaly I do all my repairs myself but this one is a big job and as the car is still under warranty I thought I'd let them deal with it.