So, yeah. this is a good news/bad news situation here.
The good news is that some respected classics are returning to TV, as Yogi Bear is back in the UK. However, he's not on Boomerang, he's on a different kids channel.
At the moment, Yogi Bear is currently airing on POP, A UK channel only available on Freesat and Sky, and has only two timeslots on weekends at 6:30am, and repeated at 10:30am. The channel also currently airs the Smurfs, since the release of the films, and a formally aired show on CN/Boomerang: The Amazing Adrenalini Brothers.
I have no clue as to what show they are airing, whether or not they include Snagglepuss and Yakky Doodle. Yakky seems to appear on the show page. http://www.popfun.co.uk/tv-guide/1136/Yogi-Bear
UPDATE: According to the episodes of the TV Guide, it is The New Yogi Bear Show (80s series).
So, it seems Boomerang isn't giving much thought for their classics at this time. Hopefully, there might be a weekday slot for Yogi, or some other shows coming back.