Legal advice on what exactly?Insure against what happened to the OP by spending money on legal advice
The lady in the linked article appears to have given her tenant the requisite notice of termination in accordance with the law as it existed at that time.
Her problem is that the Government subsequently changed the goal posts and the effectiveness of her notice has now been paused until next April - assuming this date isn't further extended.
No advice in the world would have avoided this scenario.