Is there a company in gatwick airport who will guide someone travelling through the airport?

Register the person in advance for Special Assistance, or just ask for it at check-in if the help is only needed once the passenger reaches Departures. If the person is disabled in any way, even if not registered disabled, they will provide the level of help needed. For instance, if the person is slightly learning disabled, or a bit mentally confused, or extremely nervous, or has a broken leg, or is just not able to walk so far. They take them through in a little group, maybe walking alongside the wheelchairs, or they might even get to ride with people who go in the buggies. I have also seen them help a lone parent travelling with too many small children to manage by herself. They normally board the assisted people first, and someone comes right to the plane to help them at the other end, if that is needed. There is also a special service for unaccompanied minors.

There is and they normally help people with mobility problems who find it hard to get through the airport, Phone up the airport or your travel agent and theywill arrange it for you

Contact either the airline or airport and ask for special assistance. When I was little and had to fly alone, someone from the airport was with me going through customs. Once I passed customs, I was "handed off" to an airline personnel and she took me on board.

There should be staff from the British Airport Authority around to help. If not approach anyone working on a customer service or information desk. or anyone else that doesn't seem busy and can help. Security may help too.