I used to be fortunate to have acid soil where we lived previously in Essex and I could grow all the ericacous plants that I love. However, here in Lincolnshire I don't have acid soil but I still grow a lot of the plants I like but I put them in pots. I have three Pieris that have been in pots for five years. I renew a good third of the soil in early spring and feed with ericacous feed and they have really done so well. I think that you may be able to replace some of the soil in the ground but in the end I think it might be better to just go with the soil you have and put the plants you want to grow in pots otherwise you are always fighting with nature.