I don't think patriotism can exist without, at least, a bit of nationalism. Patriotism means putting your nation first and others second, and it is very hard to do so without also putting more value in your nation than others - which is a proto-nationalism.
First, small relapses happen. Second, leaving the EU doesn't mean they've rejected the idea of globalism (just look at how urgently their companies are establishing trade relations with Europe right now, foreseeing the upcoming change), they've just denied its particular implementation.
Even after quitting the EU, the UK still is going to have a very advanced immigration system. Many people don't realize that, but, even given how hard it is to move from poor countries to the first world, countries like the UK still have a much more open system in place than most other places. Try to move, say, to China - they barely have a functional immigration system there, getting citizenship is a nightmare, and likely you will always be perceived as a second-class citizen. The UK is still going to be much closer to globalism than, probably, 95% other countries.