Hi Jo and welcome. What an amazing sweetener to go with caring for your Dad, your own smallholding
Womble has said just what I was going to - start small and slow. There's no set way of doing things and there's no such thing as the Smallholding Police, making you follow a set plan - it's yours to work as you decide.
It's worth taking the first year to learn about your land, its climate local and micro, the soil in various places, as it's likely to differ over the whole area, wind directions, temperatures in a normal year, first and last frosts.
Have a think through your ideas and how they can be adapted to your new reality, and those which are perhaps unrealistic. Meanwhile, keep the whole place at a tick-over, so you learn what the very basic, minimum work entails and how long it takes - mowing lawns, cutting hedges, weeding existing flower beds. That gives you a base line when calculating how much time you will have available for growing your own food.
The first thing many folk do, me included, is to get some hens, maybe half a dozen at first, to learn about their care and to provide the family with lovely fresh, free range eggs.
You could decide to buy a coop (their capacity is always over-estimated by the manufacturers), or you may decide to build your own or adapt a garden shed.
How many of you will there be at home? How many will be interested in helping with the work, because there is a heck of a lot of work in maintaining five acres, especially with the time you will spend as your dad's carer? There are always jobs which need two people to manage.
The very worst thing you could do would be to launch into keeping several different types of livestock, find yourself overwhelmed and end up hating what was previously a dream. So keep it gradual and learn as you go, introducing a new step once you've got to grips with the previous one.
Above all, good luck with this lovely new venture, and we're all always here