Traveling DFW-LHR in J on AA. Because I arrive at 815a, I may not have access to my hotel in London, so I was thinking maybe I'd go for a run from T5 -- I have a route from T5 through the neighboring hamlets of Stanwell Moor and Poyle that works quite well -- and then take a shower at the BA Arrivals Lounge before heading into London. Am I correct that I can access the T5 Arrivals Lounge even though I will have flown into T3 on AA?