Tling a worktop and lifting a gas hob

Release the clamps to the hob be assured you would get a tile slide under ther hi. Without disconnecting the hob

Get the hob disconnected and then reconnected by a professional, a 9mm lift is quite significant when you are moving fixed copper connections. I lift of that much without disconnection and probably an adjustment to the supply pipework could lead to a leak. Not worth the risk of cutting that corner.

Depending on how much play there is with the gas fitting, you could loosen the brackets and tile underneath but to be safe maybe disconnect and reconnect to avoid damage/leak to the gas fitting

Depends if the hob is gas or electric. If it’s gas I would get a professional to remove the hob and reconnect after. 9mm is quite a lot and might cause a gas leak of the gas pipes are strained.