Hay making by hand isn't so bad, especially if you don't work full time. You just need to get a good spell of weather. You don't need many tools, just a scythe, fork and a rake, and you can make yourself a little hand baler out of wood (I did).
Spring grazing could be done with some cows (calves maybe best?) and/or sheep - probably best to loan in some from a near by farmer. The farmer can tell you how many you need depending on the length of the grass. Don't buy your own stock in just for this, it's not worth it.
You need to remember that every time you cut and remove the grass you are taking away nutrients. If you have stock grazing it then they are putting the nutrients back into the soil via their dung. Also, I expect you will want to let it go to seed too - but if you do that then any hay crop you take off it has less nutritional value.
There is a NT meadow in the next village to me and they sometimes have wild ponies grazing it off or cows, or they just flail mow it and leave the cut grass to rot down (which makes it look awful for a couple of months but is probably very good for it). Maybe it would be worth you trying a few different ways out and see what works best? Or vary it each year?