I have my plan developed.
Instead of telling my parents "I'm going to London with a bunch of people I met on the internet", I tell them I'm going with my friends for one of their birthdays, getting her to drop me off in the car at my friend's house, who lives about a 10 minute walk from the train station, walking to the train station then catching the train
Except as I was typing this, I realised I'll be able to drive by then. Shit, that's scary