Octavia VRS Seat lower bolster

Hi, I'm looking for advice and guidance on this one. I have an Octavia 2008 VRS estate. I love the car but its now at an age where little things are starting to fail.

The drivers seat is showing signs of wear and the seat bolster on the right hand side is digging into my thigh and causing a dead leg on longer trips. I've attached a picture of the seat and you can see the fabric all creased. Would you say the foam bit in the seat needs replacing and is this an easy job for a competent home mechanic to do or best left to a dealer? Any ideas on costs of the parts and any you tube or photo guides anywhere on how to do this. I imaging the seat has to come out, but it has an airbag, so can i just disconnect the battery and be safe? The bolts holding the seat in look  like the the spline type, is it a 10mm size required?

Thanks in advance.