If he has the cash to buy 100 milkers then he has £100k ish? Why not buy a bit of land and play about in evenings and weekends. Best of both worlds.
I'd say go halfway house. Find a herdsman position,milk someone else's cows,live in the house provided and earn £30k if you are very good at it with no risk.
Agreed- better to try and (hopefully not) fail at something than spend the rest of your life wondering, what if...?
Milking on his own to tying for a young fella, before he knows whats hit him he will be middle age and skint.