Hi thanks for the reply, any boards you can use multi finish on. Ever used knauf pink fire boardsIf you line it up properly and get the nice edges bang on tight then there's no point even plastering it inside. You want hetas approved boards, there's loads of them about, victas do their own range. If you really want it plastered then use the victas plaster but be prepared for a lot of swearing as the stuff is wank
Wot Kasper said - Vermiculite, cement board, etc but nothing with Jism in it.