Hi, welcometo GoY, a lot depends on whether your soil is acid or alkali, if it's acid, you cangrow Rhododendron, Camellia, and many more, most shrubs will stand a slightly acid soil, some must have an alkaki soil, but the list of shrubs is endless,the first thing you need to find out is your soil ph, and take it from there, the ants will not bother shrubs or trees, and you will never get rid of slugs, the best you can do is try to control them, especially when the ground is moist, Derek.

The ants won't hurt shrubs unless they make a nest under the roots, so don't worry about them. Most of us have a constant battle with slugs but if you like you could google Slug resistant plants where there's lots of suggestions.