well, of the three points raised by kit fitters electrician.
1 the board should be the right way up, extend tails, turn board, job done
2 nothing wrong with tails from what i can seen think they are double insulated, he probably had not see these red/red & black/black tails
3 if the sockets on the circuit in the kitchen he added to, may reasonably be not expected to supply portable equipment for use outdoors i.e. if the kitchen was between other rooms with no door to the outside then he could argue the point of no rcd on circuit he added to. i would guess tho that this circuit could be expected to feed outside. if it was my companies job we would have installed a split-board and i dont really understand why he didnt.
the main earth should be 10mm. gas & water bonds also in 10mm cross bonding required(for the time being) in your bathroom(s) 4mm
tell him you will call in the niceic area inspector if he doesnt address these issues.
as for tidying up other electrics i dont really know what to say, its not pretty but probably not really dangerous. also i bet the fuse-board was there before the boiler, try asking the plumber to move it, joking