The Teaching and Learning Materials, a growing library of resources offer excellent support.
The exemplar answers with examiner comments provide a particularly valuable resource. These booklets look at questions from the AS and A level Sample Assessment Materials, which was used in the trial undertaken in summer 2017. Real student responses are shown together with commentary showing how the examining team apply the mark schemes. The commentary includes always useful notes on common errors.
Edexcel Sample Assessment Materials
These could be used in class and students asked to find errors. For such a question we can, of course, illustrate the solution with a little technology, something I believe we should do at every opportunity.
A complete set of worksheets to support the transition between GCSE and A Level is available. (Scroll right down the page and select ‘Show more’)
Note the support for Statistics. The Teaching Guide is very thorough indeed, as Edexcel say:
“This booklet looks at statistics content of AS and A level Mathematics qualifications and is intended to offer explanations of the terminology that is being used in specifications, guidance on how to approach teaching of the content and help on where and how to use technology to support the delivery of the course. This document is designed to give teachers a starting point and does not include all possible approaches to topics discussed.”
For further information on the Edexcel specification and sample materials see this page.
Signing up for the wonderful Mathematics Emporium is highly recommended, note that it is a free website intended for the use of teachers of mathematics in secondary schools, regardless of what board you use. Register for an account and ensure you supply a correct centre e-mail address in your name for verification, your centre name and centre number.
Some of those old A Level papers could be rather useful I suspect, a useful source of questions.
See also Mathematics A Level 1986.