Hi from the Blackdowns and welcome!
You've had some very sage advice from everyone on here. For what it's worth, here's mine.
Fencing - If your boundaries aren't that great (or even if they are), invest in some electric fencing stakes, wire and as many 12v batteries as you can afford - One on the fence, one on charge and one in readiness just in case. If you have vulnerable stock like poultry or lambs, electric is the only thing that will keep out the foxes. You can get some quite good Solar trickle chargers, but have backup batteries.
Water - Most important thing for your stock. It has to be clean. Sheep prefer still water (a trough as opposed to a stream), pigs like a bit of a flow and somewhere to wallow and cattle don't like to walk more than 20m to get to it.
Livestock - We have sheep, pigs, cattle, ducks and chickens. I would start with pigs and chickens. They are low maintenance and a joy. Sheep and cows are harder work. Some people say that sheep's life ambition is finding new ways to die...! Pigs are great to start with. Get a couple of weaners to have over the summer (if you get some end of May/beginning of June, they'll be ready for slaughter in about November) and use as cultivators/fertilising machines. We are using ours to clear some neglected orchards and you get a double benefit of amazing meat when you come to slaughter them. You can double up with your chicken house in amongst your pigs and cut down on poultry feed and fencing. They will live quite happily together and the pigs act as another fox deterrent. You may have to hunt in the pig arc for eggs, but hey ho! Pigs are the ultimate smallholder animal. You can use everything from the carcass and, if you get fatteners, you aren't committing to year round care to start with. They ease you in gently!
If you are interested, come and see our setup. We aren't far from you and would be more than happy to show you around.