Your employer has 10 days from your final work date to inform the Home Office that your employment has ended. Shortly after your employer has informed the Home Office, you will receive a *curtailment of leave* advice from the Home Office stating you must leave the country within 60 days or by the end date on your visa (whichever is earlier). I think one issue for you could be timing, especially if your employer informs the Home Office promptly and the Home Office sends you the curtailment letter immediately. Your trip to Ireland could then mean that you would be deemed to have left the UK (although much sooner than the allowed 60 day maximum), and hence would not be eligible to return using your current visa.