Dear Scott,
I had the same question in June last year. After I ordered my Super 3 in March, I wanted to go and visit the factory in June. Living close to Zurich/CH I flew to Birmingham with the intention to rent a car and drive to Malvern. When I arrived, not a single rental car was available (I made no reservation, my bad...). So I took a taxi and spent a small fortune. On the way back the receptionist at Morgan told me about the Malvern Link train to Birmingham, which did cost about 10% of the taxi...
So I would warmly recommend the train.
Enjoy your visit, it is a genuinely great experience if you are into cars!
Kind regards,
Adrian