I've used the LHR arrivals lounge in order to shower, blow dry my hair and have breakfast before going straight to the office (not in central London) to conduct meetings. I would feel really icky without a shower, and as the hotel I stayed at was further from the office than the airport it made no sense (timewise as much as anything else) to go there, try and get an early check in, shower, and drive back to the office. Arrivals lounge = godsend for things like that!