Multi purpose will be okay, or a mix of ericaceous and John Innes No. 2 even better.

Ah Bamboo I thught they liked ericaceous compost have I made a mistake in buying it for mine? Want to keep mine in a pot

Well there's some confusion over this - Acers dislike alkaline, chalky conditions, but they are perfectly happy in neutral soils, and most multi purpose composts are neutral, so the idea that they're acid lovers isn't really true, it's more they don't like chalk. It'll be fine in ericaceous though.

thanks for clearing that up