Hi, been tiling on and off for many years. My question is, i'm about to do my kitchen floor and I wanted to check what i'm about to do is the correct way as it'll work out a very costly mistake, I just wanted to know about the correct procedures

The floor is concrete with patchy SLC that is under vinyl tiles, and i'm looking to install UFH mats and porcelain 600x600 tiles. . . so. . .

1. Prepare sub floor with primer
2. Use flexi adhesive to fix insulation boards (are they always necessary)?
3. Fix UFH to boards
4. Use SLC to cover entire area at a 2-3mm thickness?
5. Use Rapid flexi adhesive to fix tiles.

Can you guys recommend the right products, I normally use BAL rapid set flexible?

As said, I need to get this right as there is alot or prep work and an expensive mistake if I missed something out.

Any advice and comments are more than welcome and thank you in advance. .