Hi Mark,
Good to see another log from a fellow Brit. I write my log in kg rather than try and translate everything into pounds.
A couple of common questions: what are your height and weight? These help give a bit of perspective on how well you're progressing.
For warmups I think the book is pretty clear (you do have the book don't you?), but as an example, if I was squatting 193 lbs (87.5 kg) I would do:
20 kg: 2 X 5
40 kg: 1 X 5
60 kg: 1 X 3
75 kg: 1 X 2
87.5 kg: 3 X 5
You can try and get really precise calculating even jumps, but sticking to round numbers makes it easier when changing the plates. I take enough time on the warmups that I don't get out of breath and fatigued, but there's no need to wait around. I would however take a decent rest (perhaps three minutes at this stage) before the first working set though as you want to be as fresh as possible at that point.
Shoes make everything feel so much more stable. I'd get them ASAP. A belt is a lower priority until the squat goes up a bit more.