Mouflon are wild animals, living in the mountains of Europe. They would not be happy living in the lush lowlands in Suffolk
The American version is the Bighorn sheep and again lives in the high mountains. As Fieldfare points out you would need a permit to import and keep a wild animal, along with all its safeguards and regulations, inspections etc and with no experience of keeping wild animals it just isn't going to happen.
Soay are mouflon patterned, as are Castlemilk Moorits and Gulmoget Shetlands, although none have the big horns of the native animal.
Cross posted with Jimmy84: I think wild mouflon are a completely different kettle of fish to wild boar which are very common. The welfare of your animals should come long before your commercial needs and I can't see how a wild, mountain creature would ever be happy in any environment you could provide. I sound negative because I am