tamaris, are you going on holiday or moving house? If you are going on holiday have you considered taking a 10kg bag as cabin luggage - it is far more convenient.
British Airways has size limits on its checked in luggage:
Standard checked baggage
Up to 90 x 75 x 43cm (35 x 30 x 17in)
Up to 23kg (51lb) in Economy and Premium Economy
Up to 32kg (70lb) in First and Business