Degree's are a good thing in certain areas of design, but in Graphic design I would say experience will out weigh qualifications.
As i mentioned before, there is a huge amount that a degree will not teach you, and you would learn far more from being in a workplace (if you push yourself), and be a far better bet for an employer.
We recently took a new guy on, in the interviews we held, our main concern was looking at the type of work they had produced, what experience they had in the work place and what creative skills they had.
The guy we chose studied at college, was working for a travel company creating the holiday brochures, but had done work for local bands and independed clothing shops - his designs for the later were very stylised, creative and original, whilst he ability to lay up complex jobs quickly gave him a huge advantage over anyone else we saw and we picked him.
Having said that, a job in the automotive design market would deffinately require you to have a degree before being considered and would be a huge benefit.
My adivce is spend the next two years while you are doing A-Levels researchhing and speaking to people within the trades to see what they would be lookinbg for, asking to go on visits and sittin sessions to get a feel for what the job would be like.
I do think it is a shame your not going to college, this would have been a great experience, and really matured you whilst focusing you into a trade.
I knew no one when i went to college, firswt couple of days were a little strange, but soon got to know everyone and loved it from then on.
Coventry University has a great reputation, I would imagine it is very difficult to get into so I would start maing contact now if it is a possible option, ask to go and see the university anfd meets some of the tutors, this can only do you good to be know to them and to have shown a really interest in them so early on.
Speak to them and see what you need to do to secure a place, they should be more than willing to offer help and advice.
Matt