Seeing a few posts that mentioned respondents liking to hear back from the person asking a question, I thought I would report back belatedly about my Heathrow airport experience.
Most importantly ;) I was able to successfully sneak into the bathroom and freshen up before meeting up with my friend who was picking me up: mission accomplished!
I did have a blip along the way, though -- shortly before taking off from San Francisco International to Heathrow (via Virgin Atlantic), the captain announced that some of our luggage was being taken out of the cargo hold: something about the one cargo hold being unusable. This generated a collective gasp... I checked the Delta app (the airline I booked through) and indeed, my rolling duffel had been removed. No announcement was made in terms of where the luggage would go or when or how we would be reunited...
(I totally get that this is one of many reasons why people like to only do carry-ons... I'm not one of those people, though.)
Anyway, I overheard a flight attendant tell someone that the the baggage would go on a different plane... I asked a different flight attendant who was passing by if she knew anything... she said that she didn't, but people keep asking her... and she certainly hoped that they simply removed the luggage and put it back because she had also checked a bag...
I was on the 5pm flight out of SF... I knew there was one that left at 10 pm. I was picturing my friend and I waiting around Heathrow for 5 hours for my luggage. I wasn't sure how it worked. I was frustrated by the bad communication. I should have tracked down the flight attendant whom I had overheard but of course they were all busy, and I know how it is to work in a public-facing job where people are asking you questions about things you aren't sure about and can't control.
So I forked over a few dollars to connect to Wifi and texted a friend via Whatsapp who passed along the Whatsapp contact info for Virgin Atlantic customer service. I did connect with Virgin Atlantic customer service via Whatsapp, but they didn't know anything concrete as regards the flight, except they did tell me that most likely, the luggage would be delivered by a courier.
I was frustrated the captain told us that the luggage was removed but didn't say anything else... surely he knew the protocol.
I texted the friend who was picking me up to let him know what happened... he's pretty cynical about the state of the UK these days, and wasn't surprised. (I believe his exact response was, "Bloody broken Britain...") I don't share his cynicism, but I CAN say that very late the next evening, when the courier delivered my bag, he realized he had delivered a bag to the address before...
After getting everything sorted, my friend and I spent a lovely week in Wales... and even got a "bonus" day when Virgin Atlantic canceled the flight until the next day (more bad communication in that arena, but that's a whole other thing).
Lastly, I told my friend about parking at McDonald's or Costco to wait for me, but he didn't end up doing that. When I saw the price tag for a few minutes of short-term parking, as people had mentioned ("daylight robbery!") I was very sorry he didn't, and will mention it again next time.
I should also say, I was very happy that I had decided to go with the REI rolling duffel in the uglyish yellow/green shade that I believe I mostly picked because it was on sale... stands out well from all of the black bags and in a situation like this, seemed especially helpful for being distinctive. Liking to document a lot of my trip photographically, I had had someone take a photo with my bag before leaving for the airport... turned out to be a good idea, so I could show the airport employee what it looked like when filling out the paperwork once I landed.
Thank you all for all of your help, and to the extent that it's interesting, I apologize for not sending a more timely update...