I need to get my gas boiler replaced (pretty urgently as it's died and
I'm living off the immersion heater and warm pullovers at the moment!
SWMBO unimpressed). Before I get a Man in to do this though, I want
(need) to sort out the electrical dog's breakfast left behind by the
installer of the original system.

Basically, there's a 4-core-and-earth cable emerging from the ceiling
with a single-cored mains cable taped alongside it; these simply dangle
down the side of the boiler (Vaillant Ecomax VU226 EH, sited in a corner
of the utility room) to underneath it, and then dissappear straight up
into a terminal strip. So - no switch or FCU, and four feet of loose
mains cable hanging from the ceiling. I now want to sink the mains
cables into the wall and terminate them in a switched FCU, from which a
short (presumbly 5-core?) flex will emerge and connect to the boiler.
This will probably involve lifting the upstairs floorboards immediately
above the boiler to install a juction box, as the existing cables are
probably too short. But AFAIK there's no such thing as 5-core-and-earth
cable is there? What am I missing here?

I think I'm going to have the exisiting boiler replaced with a W-B 30CDI
condensing system boiler. For simplicity I was intending it to be
controlled by the existing 7-day Sunvic HW/CH programmer upstairs in the
airing cupboard which is really the 'nerve centre' of my system, and I
will need to add in a roomstat (don't have one currently and so was
going to add a wireless one).

Any advice as to the best way forward would be much appreciated. Should
I go for a new combined wireless roomstat/programmer - would that remove
the need for anything other than standard 2C&E cabling for the new
boiler? If not, what? (I should add that it's a long and complicated
route for cabling through the house between boiler location and airing
cupboard, which I really don't want to have to disturn and fully rewire)

Many thanks
David