Thanks, I did a bit more research and watched a couple of videos and it's started to click in to place.
From what I've read, its not worth the brew day effort to brew less than 5 Gallons (or 5 mini kegs (25L) in my case).
But as that means I'd need 2x sized kettle which is expensive, I'm thinking I'll hang on before starting All Grain.
I've very practical, and have some background in electronics (and I'm a software engineer), so I'm thinking I'll buy a plain 50L+ SS kettle (it looks like 56L is the magic number???) and a bag, and start brewing manually on my cooker, cooling overnight (until I decide to build a coil)
Then, when I've got a bit of experience, I'll consider investing in a SS tap, thermometer probe that can be hooked up to a raspberry pi / arduino and a relay that controls a kettle element. But I don't think it's purchase expensive equipment immediately ha.