Hi Andy,
I claim no expertise in workshops, but offer this insight. My first model boat was scratch built on the floor of my student digs with a small range of hand tools, and I had a heap of fun building and sailing it. Fancy equipment and setups give you more options, including some “better” ways to build perhaps, but I don’t think there is any minimum requirement.
My suggestion for starting out, for what it’s worth, is to begin with a good sturdy bench with good lighting, a cutting board and a small range of good quality hand tools. If you want to invest in electric tools then a small pillar drill is essential for drilling precisely, neatly and perpendicular to the material. This doesn’t have to be expensive, so long as there is no lateral play in the spindle and the spindle doesn’t wander when lowered and raised. Others, with more experience, can advise on more advanced equipment. I love using my lathe, but have yet to find an essential modelling use for it!
Mark