Sooty's had lots of breaks, changes of formats and the companies producing it as well, Blue Peter hasn't.
What time did it change from a studio show in front of an audience to them living in a house? I presume around the time Matthew took over.
Appears to have been around 1981, as they were doing inserts into the previous show as per this example from 1980 (all nine parts of this have been stitched together to make one long video, the first insert is less than five minutes lomg):
Apparently this was remade under Cadell.