Wiring from cabin to boot

No!
You don't need to remove the T-bar..if you remove the engine cover carpet and then the insulation...commonly know around here as the dead dog..you can see a way under the T-bar....you will see the large grommet which you can poke a wire thru on the side of the shelf in to the engine bay.
Whilst there take a good look at your engine..nice looking motors.

fantastic, i'll take a look tomorrow and see if i can get further, thanks

Might I offer an alternative? If you run your wire via the drivers side
You can follow the bonnet pop cable & utilise the bulkhead holes accordingly.
I’m pleased to see that little yellow car on your thumbnail, welcome aboard, you have already sampled the rest of the crew; a better group of old salts you couldn’t wish to meet on a mess deck.
If you are intending to pick up the reverse light voltage to enable your system, I would be inclined to solder a wire on to the appropriate connector on the bulb board.
You are well advised to grind the top surface from the contact strip before tinning the strip.
M

I was about to suggest you do exactly what Airportable suggests.  If you get a low coolant alarm kit the instructions will direct you to use this route.  No need to remove The-T-Bar.  No need to remove the engine cover either, unless you need to get at the reversing light connections.

Thanks for all the help guys, it was much appreciated and was another great learning experience, the camera is now wired up and working, discovered how the back of the roof lifts up and now know where to run the wires for the coolant alarm too so that'll be much much easier when i do it, they seem simple enough, stick the sensor to the tank, stick the speaker where the driver can hear it, and find a 12v switched supply, winner.
Anyway, here's the camera poking out;

(Don't worry i'll be putting fresh plates on her at some point, just need to decide if i'm changing the reg first then i'll get some recreation dealer plates made up)
Thanks again everyone, i'm incredibly grateful for the guidance.

Well done! Looks good too.

If you were to buy a coolant alarm from  @BruceTF135..you will find the most concise instructions you will ever read together with pics. Even shows where to get your Live and a fitment to do it without cutting a single wire..and they work a treat.
There are of course other vendors of such equipment...

I'll drop Bruce a message after the festive season and get one sorted for some peace of mind.

Just run your hand under the header tank to see if there are any wires there, you could be fortunate in having a low coolant sensor as standard. Higher spec cars were equipped with these before the children if a lesser god received them.
Sorry Bruce I’m not intentionally trying to affect any fiscal throughput you might be relying on for a festive piss up that might be planned.
M

Higher spec cars?!
Are you insinuating that some of us have lower spec cars? That don't need @BruceTF135..of this wonderful invention?
I find that cruel and heartless...especially at this time of year...beat yourself up with a suitably stiff twigg!
 

Even at this Yule tide you’ll have to face reality, no matter how hard it is to come to terms with. Sobbing over another’s disappointments illustrates your compassionate side but if you listen very carefully you’ll be able to hear a solitary giggle & it could be Bruce imbibing an excellent single malt bought with the proceeds of his labours.
Your tears will only soggy the yoke log & no one wants a soggy log.
M

Airportable wrote:

Even at this Yule tide you’ll have to face reality, no matter how hard it is to come to terms with. Sobbing over another’s disappointments illustrates your compassionate side but if you listen very carefully you’ll be able to hear a solitary giggle & it could be Bruce imbibing an excellent single malt bought with the proceeds of his labours.
Your tears will only soggy the yoke log & no one wants a soggy log.
M

😁😁😁😁

Ok..you win..😉
 

I've heard tell that there are some folk that quite enjoy being beat with suitably stiff twigs! So one should check before issuing such a punishment, as it may be taken as a reward.

Although I've not heard of soggy log enthusiasts, but it would come of no great surprise to hear that there are folk with such interests.