I grabbed this map which shows the situation on
18/June for HU citizens as
tourists (hence the white spot in the middle) Might serve as a general reference
(light green - open, free togo, dark green - opening soon, yellow - quarantine, etc on entry, red - not open for tourists)
The UK should obviously fall into the yellow category. Note that for Baltic and Scandinavian citizens the reds in the North are mainly light green
HU citizens do not need to self-isolate anymore, no matter where they return from anywhere in the world.