Well there’s the thing, as I am sure you know GDPR comes into force in May 2018 at which point your so called Great Britain will still be full members of the EU / European family and as such you will be bound to comply with until the end of your membership.
If you wish to have a carefree and lackadaisical attitude to personal data then that my friend will be your funeral.
:taxi:
Well I'm very glad that we paid for your roads as well as gainfully employing a generation of your youth to build ours and build profitable businesses thereon. No need to thank us.
And Eire and the UK have a an agreement allowing free movement between the two that predates the EU, so will be unaffected by Brexit.