I did a similar thing last year. I had stacked turves from an old lawn, 2 compost heaps, and several,bags of compost. I have the richest plantImg area now in the garden. I,planted up hellebores, Heucheras, agastaches, dicentra kimg of hearts, miscanthus morning light, astrantia jumble hole, geraniums pink ice and Elke, convolvulous cneorum,Bowles golden grass, carex testacea, berberis atro nana, Acer dissectum garnet as well as regale lilies, allium purple sensation. There are some mature plants bordering it too.
I list this because I too once had plans to make this an ericaceous bed for acid lovers. To try and make a lime/chalk bed Imto an acid one is nigh well impossible. You will need to use sequestereen, ericaceous soil by the load, flowers of sulphur and goodness knows what else. ,and the plants still,won't look happy or thrive.
Im happy with the bed I've made. The plants look happy and are,thriving. It looks good.
Trevor, at least consider not using acid loving plants there. You can make something far better for much less (wasted) effort.....!!