Head Unit and Sat nav/smartlink Upgrade - HELP???

Hi All

Completely new to Skoda and this site, so please be kind! Id appreciate any help you can give me on this.

Picked up a 2015 Octavia estate VRS DSG last week with I am well chuffed with, but I am hoping to make a few improvements.  I have surfed the forums for info and have found loads of really good stuff, but I am completely non-technical and most of the info has basically added to my confusion.  So I believe  now that I currently have a Bolero with the smaller screen and no sat nav.  Would like to upgrade, if possible, to an OEM unit with sat nav and smartlink with the bigger screen if possible. I keep reading about re-coding etc, and want o make sure that whatever I upgrade to works as it should.  so onto my questions...

1) Is this possible?

2) How do I figure which unit/diplay or combination of parts/atennas/usb I need?

3) best place to buy unit once the correct one is identified?

4) recommendations for fit in the herts area?

Thanks in advance people