Guidance sought re properly arranging mounting of CH controller.

Hi All I had to replace a seemingly-failing CH controller over the weekend (Sunvic Sunpro 2000 replaced with a Drayton 722). This reminded me that there is a roundtuit that I need to sort out - the proper arrangement of cabling around all of this.
A picture would probably be worth a thousand words, but in the absence of that, I have the following:
1) The mains input to the controller. This is 1.5mm T+E, surface mounted ;-o 2) a mains input to the ('emergency') immersion heater. This is 2.5mm T+E, under the plaster and coming into a double back box 3) a proper immersion heater switch which allows the cable to come out from the surface corner 4) the flex to the immersion heater, which comes out from the switch 'properly' 5) the flex to the CH pump (I have a 'zone C') system ;-o. 6) The controller itself backplate, which is currently rawlplugged into the plaster surface
It is how to 'properly' manage (1), (5), and (6) which I am wondering about.
- how to get the surface-mounting (1) to neatly be wired into the backplate? I don't want to change things too much. I don't mind perhaps hiding the T&E in some plastic conduit, then sinking the last few inches into a backbox. But then: - how is one supposed to get the flex to the pump out neatly/correctly from behind the backplate? I know about blank plates with one cable outlet - but *two*?
I can't help thinking that I am missing a page in the catalogues with just the right wiring accessories for my needs. Any pointers, or links to photos to show how it might/should be done?
Thanks a lot J^n
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On Monday, November 4, 2019 at 3:58:16 PM UTC, jkn wrote:

Update: I have found this picture:
https://i0.wp.com/www.automatedhome.co.uk/wp-content/uploads/2017/10/Drayton-2-0607.jpg
Which confirms part of what I thought - everything is supposed to come from behind the backplate. But: how are the two flex cables then supposed to be neatly led to the surface? I can't find a '1-gang 2-way flex outlet' anywhere...
J^n
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You could possibly get two 0.75mm flexes out of one outlet,[1] but I'd just use two outlet plates. You can get backboxes to mount two singles side by side if they actually want to be next to each other.
[1] Using Wago or similar for one of the sets of connections.
--

Roger Hayter

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But of course that's not applicable if one is direct to the immersion heater rather than a relay.

--

Roger Hayter

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