Other SO34.2 owners with the single aft cabin version may find this method of installing a combi-microwave useful.
First you need to extend 240v to the port side of the boat, I did it with running a high grade cable through the bilge from the power supply next to the navigators seat. I fitting an original style French outlet behind the microwave, but then have an a short extension lead so we can also use 240v whilst in the marina to boil a low wattage kettle.
Back to the microwave, the Breville one in the picture is a standard small combi unit with grill which fits exactly and is really versatile. You need to check measurments carefully but this one fits perfectly!
The securing of course is the most important.
My simple method was to place the microwave on to an additional board that was shaped to fit the top the locker, the microwave door is then high enough to miss the small fiddle rail - I used a standard chopping board cut to size then rebated 4 shallow holes to allow the Microwaves feet to locate, then used 2 tie-down straps, these are fed underneath the new board and easily tensioned. The surplus strap can then be cut off. The board itself was simply through bolted through the top of the cupboard unit.