Here's a diagram of the layout I'm going to start with! I don't need to complicate things with anything else at this point. I can fasten these to a piece of wood, with a bucket for the reservoir!

So the parts needed!

High-pressure pump:  So I'm looking at a 12V DC 100psi diaphragm pump from ShurFlo [~£70] which has its own pressure sensor. More on that when I actually get this all hooked up!

Accumulator tank:  Now I was looking at the ShurFlo nylon-based 710ml tank [~57 euros] with max 125psi rating. They are shipping pre-charged to 30psi, but can be altered by letting more air in? I'm still a bit confused about this. There are also many steel tanks too! And we actually have some DIY ones per this https://www.reddit.com/r/aeroponics/comments/i3qft8/recommendation_for_hpa_accumulator_tank/ which is really interesting!

Pipes: still unsure of diameter 

Filters: not required at this stage

Solenoids: not required at this stage

Sprayers: Well I've noted 'Spray Jet' with 0.016" Orifice [https://aeroponics.com/secure/shop/item.aspx?itemid=85] that should be good for 5-25 micron droplets. These can be in nylon, or brass from what I've seen. Now idea how I can even measure droplet size!. I'll give those a try since they are kinda cheap !