Tiling Upstairs Laundry Room - many questions

[InteriorDesignHell]

Poking around on YouTube and forums, it seems that this can be quite complex.
Some or all of the following may be required:

adding more boarding on top of the standard 80s (I'm guessing chipboard) floor surface
...and
Waterproof membrane on floor
...and
(At some point) some kind of rubbery layer to absorb movement & reduce chance of tiles cracking(?)
...and also
?? skirting tiles??
...and not forgetting
I'm guessing a slight step up into the room might result, so something is required here that reduces trip hazard
..
And who do we ask to do this? Bathroom fitter? Flooring specialist? "Tiler"?

Like most people I've heard 1001 cautionary tales of renovations gone wrong and I'm aware that people will naturally say "of course I can do it" when they really don't know what they're doing. And then you find this out a year later.

Any advice gratefully received.

Not an expert but have had 2 bathrooms tiled

I think most of it depends on your sub floor. So if it is floorboards then the tiler would screw on some mdf so it is really flat and tile on top of this. If its concrete then they'll probably poor self levelling stuff to get it really level, then tile on top of thatb. Imo if it's just a laundry room then any type of waterproof membrane is just overkill. If it's an 80s build it's likely its concrete sub floor so they'll probs pull up the chipboard and pour the self levelling stuff on top.
You don't need to use tile skirting boards specifically. They can either tile all the way down to the floor or use regular wood skirting boards.

If you're in London I can recommend an amazing tiler who did an amazing job in both of our last 2 properties!