I need your help, please! We are flying into Heathrow in September. We are renting a car and going to Canterbury, Dover, Arundel, Salisbury, and Bath for a few days before proceeding to London. My question is, when we return the car to Heathrow, do we go inside the airport to get to the tube for our travel to London or do we have to go through security? I was just worried that we wouldn't have a boarding pass. As you may have guessed, this is our first trip to the UK and we are trying NOT to have any mishaps! Also, we will be going to the Paddington Station. Thanks in advance for your help!