A 66-year-old woman with a mental handicap s to leave Ireland for the first time when she visits Cambridge this weekend to see a play in which she ids the central character. The Play - Beautiful Dreamer - is about the life of Mona Corbett, who has been cared for in a convent since she was ten. It explores how people have been drawn to her despite her impairment. It is written by her brother Patrick Corbett, who is a leading light in the Cambridge-based Irish Theatre Company. It opens tomorrow at the Cambridge Drama Centre (0011 - 1223 - 322748) and finishes on Saturday. Mona will be accompanied by a nun.