Anthony, it is not so much how difficult it is, it is more a case of access which makes the fitting difficult.
If you are just doing a straight replacement of what is already there, then remove any obstacles under the sink to gain access, assuming you have already drained the water, disconnect the waste pipe from the sink, and the water pipes to the taps, which may be held in place with Jubilee clips or John Guest (press fit) fittings.
The single pillar taps are held by one large nut on the stem, undo and remove the tap, disconnecting the wiring to the tap, if fitted.
The sink will either be held in by screws through the upper lip, or clamps under the sink, remove these and ease the old sink out, it will be sealed to the worktop with sealer, so may be difficult to move at first.
Fitting is reverse of above, fit taps first, and pipes, then sink and waste.