Nice idea, but the Beluga is a specialist freighter built to carry airbus sections between the various airbus factories. Aircraft sections tend to be low density, i.e, voluminous but light. It's based on an A300 which in the freighter guise only had a load of 35 tonnes (I think) which doesn't make it particularly useful compared with a 747 freighter at about 110 tonnes.
The Beluga is available for freight charters from Airbus I believe.