Depending on your horses, if you have good doers you really don’t want to be adding clover to your sward as too high in starch. Also regular seed mixes usually contain rye which is not horse friendly, too high wcs levels. Cotswold seeds have rye free meadow mixes.
I am restoring my land and regular topping is making a big difference. I don’t want to spray because the forbes and herbs in the meadow will be killed and they are very beneficial to horses - I am trying to get up to 15 different plants per square metre in the sward for better quality grazing. Getting an albreicht soil analysis done (forage plus offers this service) which is targeted towards improving soil mineral balance to support meadow grasses is the first step if you are interested in regenerating the land in a horse friendly way. Agricultural contractors are focused on cattle & sheep needs to increase milk and meat yield which is very different to what horses needed -cattle pasture is too rich.
There is a great online resource called Equiculture which is dedicated to horse specific grassland management.
Strim your nettles, let them wilt and then offer to your horses to eat -really good for them
Jane not Greg
There are some seed manafactures that will include equine specific rye grass
It's the ryegrass designed for cows that is obviously no good
Timothy is also good to be included it's better than medow hay in some cases as less sugars in it
It's very popular with owners of old or low work horses and horses with laminitis