Dear Sam,
I am absolutely thrilled that you are finally arriving in London next Tuesday! I have been counting down the days until your visit. Unfortunately, a last-minute work emergency has cropped up, meaning I won't be able to reach the arrivals hall by your landing time of 3:00 PM.
Could you please wait for me in the cafe located just opposite the main exit in Terminal 5? I should be able to join you there by 4:00 PM at the latest. I am incredibly sorry for this inconvenience and hope it doesn't dampen your excitement for the trip.
Since we haven't met in person before, you might be wondering how to spot me. I am quite tall and will be wearing a bright mustard-yellow raincoat, which should make me fairly easy to identify in a crowd. I will also be carrying a dark green rucksack, so keep an eye out for that as well.
I really appreciate your patience and cannot wait to catch up properly once I arrive. See you very soon!
Best wishes,
Alex