Looks like what is known as an 'adjustable cup and cone' bottom bracket. That means the bracket can be disassembled, and the axle and ball bearings will come out; also the clearance between the cups and cones (the surfaces the ball bearings run on) can be adjusted. This differs from a 'cartridge' unit that is pressed together and cannot be disassembled or ...
OK, I eventually worked out the easier way.
The locknut has a hole in the end which, in addition to taking the skewer when fitted, has a hex socket for a 5mm allen key. Turn the hex/allen key anti-clockwise relative to the cone spanner to undo.
Would a beam style wrench be just as good, or more suitable than a click-type?
Definitely not. With a beam-style wrench you have to accurately observe where the pointer is on the scale. That means you have to be looking straight-on at the scale. Bicycle bolts are at all angle and orientations, which means looking at the scale will be very awkward.
I have only a 2-24 Nm click type torque wrench and coincidentally the main job I typically use it for is the pinch bolts on cranks, but also when attaching carbon parts like bars, less frequently. The 12-14 Nm required for Shimano pinch bolts is right in the middle of the tool's range and that gives me a warm feeling inside.
Of course carbon parts require ...