I was an engineer, but not cars.
If you're an engineer, you can change a crank sensor, it's secured to the engine by a single 10mm bolt, and one plug.
It's easily accessible from the RH wheel arch, so nothing else needs removing to get at it, just turn the steering to the right to make more room, easy.
I certainly wouldn't be carrying an ECU diagnostic tool and multiple spare sensors around in the boot. Think of the hit to your fuel economy with all that gear Nodge68. My AA membership card weighs 5grams
The diagnostic tool I use weighs less than my phone, and displays all the issues on my phone.
The sensor is tiny, and maybe 50 grams, so no change in fuel economy.
I'd rather be able to diagnose an issue at the road side, and fix it too, rather than waiting hours for a break down service, but have RAC as a backup.
One thing I wouldn't do, is line the pockets of a greedy LR dealer, who is charging way over the value of the work they did.
But as long as you're happy, I guess that's all that matters.
Keep a spare in your boot, as they're known to fail, somtimes in short secession. This because the plug doesn't make a decent electrical connection to the sensor, which causes voltage spikes in the unit, causing it to fail early.
The AA have diagnostic equipment, and will fit a sensor, if you have one to give them.
