How can I fix my lawn?

I’ve recently moved into a property and the garden is in a bit of a sorry state. The previous tenants had a dog, and I think it’s wrecked the grass and dug holes in it. The grass is super patchy and uneven, and has moss growing through it. I’ve never really been into gardening, and my last house didn’t have a lawn.

How can I fix it/make it look better on the cheap? Thanks!