How is the rear Skoda boot badge held on? I assume it is pushed in via small studs.

Nope, just adhesive. It has 2 locator studs which will leave holes tho AFAIK

Heat the badge with a hair dryer or heat gun and use something like fishing line to remove the badge.

Mines needs replacing as there is some corrosion on it. So I thought I might replace it with an aftemarket badge rather than the Skoda one.

Yeah, I'm doing mine with dome resin badges when they get here.

The front and rear's are 80mm and the wheel centres & steering wheel are 55mm.

I replaced the wheel centres with genuine Skoda ones. The steering wheel has a resin vRS badge. Might get the same for the boot badge.

I was going to do that but found something a little different so it will be off with the skoda.

I'm just not looking forward to doing it in the cold.

I have replaced a few .....use a knife CAREFULLY to remove the badge which is stuck on with adhesive. I sourced the aftermarket part from JHM Butt (Bawtry) www.jhmbuttco.co.uk

I've got some carbon fibre vRS badges coming.