@Pirke: it is supposed to be in an AIRAC amendment, but I must admit I couldn't trouble to check it out. But as for "requesting permission": when flying outside controlled airspace, you do not ask for permission, you never did - you did and do however inform FIS of your crossing the FIR boundary.
@chevvron: no, that is exactly the novelty: under certain conditions one can cross the FIR boundary without having filed. However as you mention "departing from a UK aerodrome" it makes no difference for you as long as the UK stays out of Schengen.
Mind you, it has been like that for a long while between Germany and several of its neighbour countries, CZ, PL, and more.