Galleries Club lounges are the equivalent of business class lounges, which serve business class passengers on intra-Europe flights, as well as on intercontinental flights on British Airways' Club World product.
There are three of these lounges in Terminal 5 - two in the A Building, and one in the B Satellite Terminal.
If some peace and quiet is what you're looking for, the B Satellite lounge may be your best bet. Please keep in mind, however, that it'll take about 15 minutes to walk back if your flight is departing from the A Building.
The Galleries Club lounges feature all the amenities that you would expect to find in a standard business class lounge, including hot and cold food, self-serve tea and coffee, an open bar, showers, and plenty of different areas for lounging.
thanks. as a emerald I always used the firstclass lounge, but the business class lounge is really great. loved it !