Should we use a backing board? How should we approach this?
Hello @borgun
Welcome to the Bunnings Workshop community. It's sensational to have you join us and thanks for sharing your question about tiling your brick wall.
Your idea of putting in a backing board is correct. To be specific, I suggest gluing Villaboard to the bricks with construction adhesive and mechanically fixing it in place with Ramset Black Countersunk Masonry Screws. This will provide a flat surface for you to begin tiling.
I also recommend having a look at these discussions - How do I prepare a brick wall for tiling? by @wonderiz and How to tile over a very old brick wall? by @ShelliOwo. These will give you more tips on what to take into consideration regarding tiling.
Here is a handy step-by-step guide: How to tile a splashback.
My best advice is to make sure to pre-drill your brick wall before you fix the Villaboard in place.
If you have any other questions we can help with, please let us know.
Eric