She's married to Christian songwriter and musician Dave Cooke and I believe goes by her married name now. Only reason I know this is that she was a member of a church that I once belonged to. Can't help you much further though, sorry.
As an afterthought Paul, Dave Cooke has been a touring and recording musician with Cliff Richard for many years now. If all other methods prove fruitless you may be able to get hold of Tina Heath/Cooke's contact details from someone connected with Cliff.