Mark
I don’t know if it’s feasible at your plot, but I tend to collect a big batch each early autumn (between now and end November). I then leave it to decompose for 12 months (my pile sits under two big trees next to a boundary hedge) and then I use it as mulch on top of beds for potatoes, allowing the worms to feed on it over the winter before planting the potatoes in spring.
I’ve also put ‘raw’ horse manure down as a mulch on asparagus and rhubarb/comfrey beds and I’ve never had a problem. Particularly with asparagus, the yields are much much better treating with horse manure than not treating at all – probably close to double.
I don’t know if you can afford to take this long before using your horse manure, but it may be the way to allow you to use this valuable resource effectively.
The stuff I get is literally just piled up in the car park of a stables and you go along with your car, fork/spade and bags to take it as and when you will.