Backer boards over plaster/plasterboard

Hello all,

Have a dot & dab wall, which was artex on plasterboard - this has at some point been skimmed - the skim comes off fairly easily.

I'm about to brick slip the wall (approx 25 kgs /sqm including adhesive and grout)

Can I ? / best option -

1. Screw backer boards directly over existing wall and tile onto that
2. Screw wood battens through into block and fix backer boards to battens
3. Score the plaster and tile onto that (don't like this as skim is loose)
4. Remove everything back to block and batten etc (more work).

Also will 6mm boards take the weight of the brick slips ok?

thanks

1 would be my choice .
2 if you want to add unsulation ( on outside walls)

number 1, but make sure you screw the boards to joists / noggins, just screwing it to the plasterboard isn't a good idea if that's what you originally meant