The BA Arrival Lounge at Terminal 5, Heathrow is located after you cleared customs on the landside area. After you exited the customs area, turn left and take the lift one floor up. The lounge is open to any passengers who are flying First or Club class on British Airways or BA Executive Gold members on long haul flights. The lounge opens daily from 0500-1400hrs, offering a full English breakfast until 1230hr. I usually use this lounge in the morning after arriving from a long haul flight, freshen up with a shower and breakfast before I continue my day.
The shower rooms (Hydrotherapy rooms) are located on the right side on the lounge with lots of cubicles. The lady who was manning the shower cubicles gave me a key and directed me to the right cubicle.
The shower room was clean with lots of amenities (Elimis shampoos/conditioners, towels etc.). I found it very useful especially after a long journey and all I want was a hot shower to start my day.
I also managed to sample a quick breakfast. The breakfast area is just behind the check in desk.
The lounge is very convenient if you are arriving from Terminal 5 and needed a quick shower/breakfast. But my favourite arrival lounge is still the Cathay Pacific Arrival Lounge in HKIA.