We will be taking our first trip in BA F class from Houston to Barcelona with an overnight stopover in London to see some friends. Our return flight is on United so I was hoping to get into the CCR on the way in for the experience. Is there any way to get into the CCR on a LHR-terminating F-class flight with the ongoing connection the next day? We are in Club Europe for the London-Barcelona leg of the flight. Will our boarding pass from the prior day work for access? Any way to get in at the end of our TATL? Thank you in advance.