I think truly producing all your own needs would be a real challenge (shoes? tools? nails?) - although I find the Laura Ingalls Wilder books really interesting in their description of a life which really did involve almost no purchased items. (Pegs to hold the house together, anyone?)
Looking just at producing food & power I would say 1 acre is not really enough land. You'd probably want to plant all of your acre up to coppice woodland for heating/cooking for a start. Of course you don't necessarily have to have a smallholding as such - we run a land based business & have a house in a village & land about a mile away which is a cheaper alternative (until recently we rented the land). Harder if you have animals though (we have chickens but in our backgarden).
Vegetables - not much land needed - you can grow all the veg (including potatoes) for four adults on two allotments (been there, done that )
Animals - you need much more land especially if you are planning to grow your own food for them - I seem to remember a figure of 1 acre intensively cropped to provide fodder for 5 goats, for example?
Vegan organic is probably a less land intensive way to go if you really want to produce all your own food - but you need to allow for space to grow fertility building crops, and it is a skilled business.
Power - if at all possible, look for land with water & a drop suitable for micro-micro hydro - massively the cheapest & most reliable way to produce your own power. Otherwise it is achievable reasonably affordably with wind (if you can get planning permission & are in a suitably windy & isolated site) or photo-voltaic (need a south facing roof & either to cut your usage to the bone or spend a lot of ££s).
I would really recommend the magazine 'The Land' (published by The Land is Ours - who are also people that you really want to know if you are thinking of trying to get planning permission to build your own place). You might also find it helpful to visit other people who produce a lot of their own food/needs. WWOOF is a good place to start, there are also quite a few intentional communities out there that might be of interest (Old Hall Community in Suffolk is an inspirational place to visit).