Solved How do I know what's what?!

I'm going through the same thing Sarah, best to take some photos preferably a shot of the whole plant with something to give scale (like a watering can) and a close up too.

I took a spade along to mine this morning and had a quick dig in each bed to see what had been left behind. I found some parsnips, carrots and potatoes. Above ground there were some runner bean canes with the old beans still clinging on. Another bed had a few onions left growing. Have a look at any plant labels left behind, that might help too. It's a bit of detective work, I made a sketch of the plot so I can work out later what to plant this year and where. You want to avoid growing the same veggies in the same soil year after year i.e. crop rotation.

As to working out what are weeds, take photos again and we will help you.

Maybe a friendly neighbour might help you point out what are weeds. You'll soon start recognising weeds, they are the ones that grow the fastest and look the healthiest