I think I would be looking for another school, pronto. I do not like the sound of this HT at all.
Insisting on logo trousers and skirts has got nothing to do with raising standards, imo, and everything to do with raising money for the school. Fwiw, our local secondary school has very sensible uniform rules - plain black trousers/skirts, white shirt, school tie, and either a v-necked jumper, or a cardigan or fleece that can be left sufficiently open at the top for the tie to be visible. Sixth years can wear a blazer.
When we moved the dses into this school (because of a house move), it was 7th in the Times league tables for scottish secondary schools, and it has a brilliant reputation locally for behaviour and achievement - people move into our catchment to get into our school.
Now, if our school can achieve all this with its current uniform policy, why does your HT think logoed skirts and trousers are neccessary.
And I am boggling at £24 on PE socks. I thought it was bad at ds1's previous school, where they needed the school rugby socks (£6 a pair) but generic sports socks would do for everything else. Mind you - that was the only bit of the PE kit that was reasonable. They had to have a rugby shirt and rugby shorts, plus indoor PE kit, rugby boots, and indoor and outdoor trainers - and all of this, apart from the footwear, could only be bought from the school shop, where it cost a fortune. At one point, I had to replace ds1's PE kit (because someone thought it would be a jolly jape to take it and hide it, and it didn't turn up for over a year) - and it cost us over £125!