During a marital dispute my husband took my personal data regarding bank account balances/account numbers and emailed it to his son, who then emailed it to a third party using his council work email. What can I do about this?
There's not enough information here to say more than "consult a solicitor, preferably (if there is one) a solicitor who is advising you on any divorce proceedings". For example, there could be an actionable breach of confidence. But to be sure whether there is one, you either need to get proper advice from someone in possession of all the facts, or do a lot of research yourself about the law and how it applies to the facts. If you do have a cause of action, then the next steps would usually be: (a) a letter threatening court proceedings unless the other party complies with your demands; and/or (b) the issue of court proceedings. But again, you would either need a solicitor or to put yourself in a position to do the solicitor's job.