Really? 14 degrees here yesterday and 12 degrees already this morning at 8am. Amazing weather considering the last couple of weeks!

The Alu and Carbon themselves will be fine, it's all the other things which will suffer from being exposed to all winter UK weather conditions - example bearings will get water in & rust from being stood. Any steel components (as Von mentioned) will have a chance of picking up rust if it picks up moisture.
I guess it depends on what your bikes are really worth to you and the space you have available. You could look at getting some kind of water/rain proof shelter/shed to protect them from the worst of it (look at some of the garden security units). I would also look at some way of keeping moisture levels as low as possible to avoid condensation introducing moisture even under a rainproof shelter.
Which jacket is that mate? Dry here this morning so I wore a LS winter jersey & gilet, not a thermal/winter jacket/jersey like I've used for the past few weeks!
Nice and clear this morning (shame it wasn't last night for the super moon) and feeling very warm (12 degrees already according to my weather app!).
Had a good turbo session last night -
'Jon's Mix' followed by some harder intervals of my own.
A 50 minute session with
3*1 minute 300W blocks (which felt easy) followed by
575W sprints with decreasing recovery (I didn't struggle to hit & feel I can sprint harder). After those were
2 blocks of
10 minutes at 90% FTP (195) which I found easy so did them higher at just below FTP (210).
I'm now absolutely convinced my FTP is set too low (Zwift has autoset it at 217, but that was on the old trainer with the tyre too tight). Rather than cool down after that I did
3 minutes high cadence at 280W,
1 minute at 400W and finished with some
messing around dropping and leading out small groups.