Science for KS3 and KS4, Chemistry for KS4, biology for all age group

I am a qualified secondary school teacher in biology and chemistry, I have got a PhD in biology. I have got more than 2 decades experience in teaching at university and 5+ years experience in teaching science in KS3, biology and chemistry in KS3 and 4 and also in teaching A level biology both in small groups and in one to one. I prefer to focus on past papers because that gives an excellent opportunity to figure out where the possible gaps and at the same time provide a nice practice in doing test papers.