So, learnings from doing the pads and discs.
First off - the fronts are easy. If you don't shred the torx head when you're removing the screw that secures the disc, then you're golden. Just don't tear off the cable on the pad with the wear sensor.
The rears are not pleasant. In fact, it's the worst thing I've ever done with tools. Getting the caliper off is fine, but the two splined bolts that hold on the pad carriage are an uttery misery if they've not been off in a while, which given how long it's been since you last changed the discs, they will be. My amateur advice from doing it:
1) Scrub out as much rust as possible around the bolt using a wire brush. Be careful not to damage any of the nearby cables.
2) Get a good quality spline bit, or preferably, a couple. These Laser ones are what I used, they're hard as nails.
https://www.amazon.co.uk/dp/B0038717EK/ref=pe_3187911_185740111_TE_item3) Get a good quality, 10mm, drop-forged ring spanner to put on the end of the spline bit. Get something well made like Halfords' Expert range, as it's going to have A LOT of pressure going through it. You will not get these out with a socket set, the torque required is horrific.
4) Get a substantial breaker bar. You won't be able to put it on the spline bit, but you'll need it to apply pressure to that ring spanner, as there's not enough room in the wheel arch to get good leverage. There's just enough room to get the spanner on the spline bit and use various parts of the suspension assembly as a fulcrum. Don't use the shield behind the rotor as it's made of cheese.
5) If it's still not budging, apply some heat. I used a blowtorch, but BE CAREFUL. You're at the fuel tank end of the car, there's wires wrapped in rubber, and you don't want to burn off all the grease down there. I needed a good 90 seconds of direct heat onto the carriage assembly, as that's the bit the bolt will seize into.
6) Get the top bolt off first. Get it off and you'll be able to rotate the carriage around the lower bolt a bit, and wriggle off the old disc. This gives you direct access to the tip of the lower bolt, so you can apply heat DIRECTLY to the bolt and carriage, which will make getting the awful, awful bastard out a lot easier.
7) Do all this on some good quality axle stands, and don't even think about doing it while it's on a jack. There's way too much wrenching around.
Feel free to correct me, but that's my experience. I'm very glad I don't have to do it again for a while.