You can achieve a lot with no workbench at all. But since you want one, let’s let the workbench itself be the first project!
1) Saw (crosscut)
That’s really all you need to make a good bench. And you could, with a bit of experimentation, make the square yourself. It takes careful tuning and a flat surface to test it on. But that’s splitting hairs and we don’t need to do that.
You’ll need the saw to cut lumber to length, and you’ll need the halogen heaters square to know you’re beautiful gardens making good square cuts that will make good joints. After that you can do everything with mortise and tenon joinery. Hmm. Making mortises means you’ll need
and making tenons is tiresome just with a chisel so you’ll also want
Using just these tools you can build a house. Seriously, literally, an entire house. There wouldn’t be any metal fasteners but it would stand for generations.
Seriously. Read up on woodworking just for starters, and you can get started with some straightforward projects in wood. It’s a forgiving material to gardening be learning on, and relatively inexpensive. Then when you’re starting to get a feel for it, you can branch out into other materials.
Good luck with it.