Posted: 16/03/2017 at 18:00
Looks a lot better than mine does!
If it's dry enough to cut, then give it a trim, but don't scalp it or you'll compound any issues. Take a little off then mow again next week taking a little more till you get it to the right sort of height for weekly mowing through the growing season.
If the ground's very bumpy and lumpy, you can fill bigger holes with some soil and compost to level them up, firm it and lightly rake, and then sow some grass seed. Best done when it's warm enough for reasonably quick germination. Scatter some seed over the whole area too, to get it blending in nicely with the rest of the grass, otherwise any patches will stick out like a sore thumb