Very easy.
You'll need to remove the trim that covers the bolts (torx screw I think) then it's just a couple of connectors and 4 bolts. Should take you about 20 minutes with fiddling and stopping to chat to remove and fit a set of seats.
Airbag light can be done later, or there and then. You need a resistor (either 330ohm or 3.3kohm, search on here for it) for the airbag connector, the pre tensioner will plug in as normal on both seats.