The Irish government is regularly publishing information on Brexit issues that may have an impact on Irish citizens living in the UK, including if Britain leaves the EU without a deal here.
There are sections on the site for different aspects of the impact of Brexit.
Brexit & You: Northern Ireland
Government advice for those driving Irish–registered vehicles in Northern Ireland and Great Britain
Common Travel Area
Full details on the rights enshrined in the Common Travel Area can be found on the Home Office website here
FAQs from the Irish government on the Common Travel Area can be found here.