That is such a wise move. You can find all sorts of treasures with a bit of patience and observation. Too many people have to be drastic and quick and ''instant'' simply isn't what gardening is all about.
I'm particularly fond of crab apple trees, and have bought some saplings from the forestry commission to grow on. They are the wild hedge variety ''sylvestris'' and have white flowers, the birds will love them, and with 4 acres of ground here, there will be oodles of space.
I just might be tempted to spend some grocery money on a few named varieties to mingle in with them
There are some pretty good comparison sites online for these trees..
https://www.treeguideuk.co.uk/crab-apple/ try this one