Here are a couple more photos for you too. One showing the skinny poured concrete patio across the back of the house and one showing all the concrete I've pulled out so far! The garden was more concrete than patio to start with

I'm struggling to get one lump of concrete out though - it's about 2ft x 2ft and the same again deep. The pole that was in it was so rotten that when I tried to wiggle it to move the concrete, the pole snapped clean off. There's now about 6 inches of metal poking out of the concrete so I've got no choice but to excavate it as it's dangerous and I can't bury it with turf but it's going to be a nightmare! I only just managed to get the other lump out by myself, although I've no idea how I'm going to move it from the pile I've made at the top of the garden haha. It's so solid I'm not sure I'll be able to break it apart as every time I hit it, it sinks into the lawn.

Can't say I advise excavating this amount of concrete single handedly, I'm pretty bruised! It'll be worth it though to get rid of it all