Camping or caravan park
Get DH on to online work finding sites. If he gets offers of work he can vet for suitability to his physical issues. Once he gets a word of mouth following he should be good. PAT testing, minor repairs, switch board stuff.
Get rid of the pony and sheep (just why!!!)
Why not go for the longer term fostering?
Are there any farmers markets near you? Any low cost, high selling things within your skills
that would work? Cakes, chutney?
If the house is large are there any parts that you could annex and rent out over the summer?
Otherwise it is vds like you are really bad at budgeting generally. Print out 3 months of bank statements and go through them with a fine tooth comb. Seperate into essential things that are unavoidable, nonessential but worth the cost and frivolous. Cut down on the last category completely, eat into the second if needed.
Completely cut out things like charity giving, gym membership, lottery payments, TV subscriptions. Move phones to Giffgaff for cheaper monthly cost, sell phones for cheaper ones.
Start a savings account. Buy in bulk. Clear and debt, highest interest first.
If none of this works. Sell and downsize.