ok its a tricky one! you are now entering stationary equipment and fixed equipment! for arguement sake! take a free standing wash/mach, this will come under stationary equip! eg. heavier than 18kg and no handles to lift! remember still no requirement to 7671 to provide isolation above! your problem! intergrated oven! put 4 screws in it, it becomes fixed equipment! now you have a problem with acc/bil to connections! If the integrated oven has handles or provision for lifting then it is stationery/eqip! long and short! no problen putting outlet behind oven!
Seeing as you're an nic man I believe it would have to be on an rcd to please the Fuhrer and should be if its in a adjacent cupboard, but not necessarily if it was behind imo. Also I would be reluctant drill holes into the next cupboard for plugtops/flex because the air flow of the oven should draw from the plinth vent below.
Also I would be reluctant drill holes into the next cupboard for plugtops/flex because the air flow of the oven should draw from the plinth vent below. Makes no difference to me 'cos the kitchen fitters and plumbers have left the plinth vent full of rubble, anyhow
The other thing is there are now plenty of accessories designed to be mounted in worktops/cupboards, like those 'pop up' sockets and those sockets that screw to the bottom of the high cupboards, so it must be ok surely.
I reckon the neatest solution that I've seen to this has been an MK Gridplus 12 module job. Switches all marked up with the appliance they control, and fuse modules next to them. This install still had unswitched sockets behind the appliances though, so the fuse changing problem still exists. Maybe better to use Gridplus and then flex connection plates behind appliances? Either way, the single gridplus control panel looks a lot better than 6 separate FCU's all around the place.
I don't know I'm wary of using fixed connections where unskilled people may meddle including other sparks :^O