Routine stuff, searching for burglars in gardens or open land, pursuits etc, no RIPA required.
Personal intrusion type surveillance then RIPA required (it isn't written like that in the act!!). There are of course, many confusing grey areas
edited to add
snurgling back to base at night with OVC at 600 and 2000m viz is not something one does often (not round this neck of the woods anyway).