Seems that there are some views here - key one seems to be the extending of the 8th April 2017 date by a further two years - has that happened - there is only a couple of weeks to go?
With my non-flying hat on - the ECJ will continue to have jurisdiction over those areas where the appropriate body has contracted jurisdiction - so still got EASA, still got ECJ - this can change but I would think it will be far down the list of priorities come 28th March.
I have flown in the UK previously albeit not for more than fifteen years - now with the advent of GPS and those lovely magenta lines I do not anticipate too many problems and do expect to have a few hours of ground to reinforce my reading.