Both Hover:bit the micro:bit hovercraft and Air:bit the micro:bit drone is part of the same product series. This means they both use the MakeKit Multi:bit control board, so you can control a vary of different servos, electric engines, and attach different types of sensors.
Good news for you
This is good news for everyone that owns the Air:bit. All you need to build the Hover:bit is the "Hover:bit Add-On Kit", an affordable kit.
This also means you can buy them together and almost get two kits in one.
For schools, maker-spaces and libraries
If a class kit is what you need the benefits are even greater. You can get a class kit with all the parts you need to build them both. For students, makers and builders this means they get a natural progression.
First, they can start building the Hover:bit where they learn the basics, the principals, they can experiment and test different theories. And when they are ready, move on to building and coding the Air:bit.