Well the Scott stuff has arrived and it looks great! I ordered the premium jersey which was reduced from £150 and it claims to work well down to roughly zero degrees.
Cyclesurgery near my office has the Castelli Perfetto in so I managed to try one on. It was nice and felt ‘stiffer’ so possibly more windproof, but for £40, this Scott top is worth keeping as a spare if nothing else. I’ll try it out this weekend and see how it goes.
I also got the Helium jersey which is categorised for 5-15 degress and again, at £35 is probably too good not to keep. Doesn’t feel as good or as warm as the Premium.