I am seeking advice for picking up someone outside terminal 4 at Heathrow. Here is the plan. My sister, brother-in-law, and I will be in London for a few days before our travel to St. Ives, Cornwall. We have rented a car from Europcar to be picked up @ noon at Heathrow. Our other travel companion will be arriving at terminal 4 at 12:15 PM. We think we three should travel from London and pick up the car and wait in their lot until we hear from her by phone (we will have a phone and she will need to us a pay phone after buying a card from WH Smith) that she is through immigration, luggage, and customs and then we can swoop in and pick her up and hit the road. This would save a lot of time versus waiting for her to arrive and then getting the car. OR, we can pick up the car and go to short term parking at terminal 4 and one of us go into get her. OR, she can go to the Europcar desk and ask them to call and tell us she is here.
Thanks in advance for all your suggestions and advice.