If you want to grow ericaceous plants in pots, you will need ericaceous compost, which is acidic and so ideal for these plants, which dislike alkaline soil. If your plants are less specialist in their requirements, you may find that the ideal compost is multi-purpose compost or one of the John Innes Composts (a loam-based compost). These were formulated by the John Innes Institute for Plant Research, and contain the ideal balance of nutrients for plants at different stages, whether seeds, potting on, or mature plants. Because they are loam-based, they don’t dry out as quickly as some other composts. However, they’re made to standard formulae, and at present include peat, so if you want to go entirely peat-free, these may not be for you unless you can find a peat-free version.
Whatever you want from compost, there are so many varieties out there that you’re bound to find a suitable sort for your purpose.