This is rubbish im afraid. I changed my own fuel tank last year and put my fuel pump into the replacement tank so same job in my eyes.
Rear axle stays in place. You have to remove the diffuser, centre section and handbrake cables. The fuel lines clip off and the sensor unplugs then one jubilee clip holds the filler neck on. After that its 5 bolts around the tank and the whole thing drops down.
I even did mine 3/4 full and aslong as your careful dropping the tank level it mostly stays inside! The tank must be dropped either way as the pump cant be removed from the access panel under the rear seats, terrible design!