Almost certainly too late to stop a whole variety of pathogens, and can't see any Government proposing rigid phytosanitary controls anyway. The garden centre trade alone must be worth a large amount in tax, and rigid controls would probably hit them hardest.
Plus, climate change (which no doubt will be vociferously denied by some!) is altering conditions so that will suit pathogens from further south.
Not a good prospect - think what happened to all the elms.