Just sorting out our summer break at the moment. We've a few nights at a hotel in North London where we'll be mostly going into London by train and leaving the car at the hotel . Then two nights in Watford and have Harry Potter Studios booked on the second day. No idea what to do on the changeover day- need to leave car park in first hotel by 10am. Any ideas on anything else fun to do in the area near Harry Potter Studios for 2 adults and a 9 year old boy who loves Harry Potter, mini golf, history and exploring?