The best place to begin is with an outstanding resource from OCR, an excellent teaching and learning resource, Bridging the gap between GCSE and AS/A Level Mathematics – A Student Guide (scroll down OCR’s page).
This is quite simply an outstanding resource for students (and their teachers!). Many exercises are provided and the answers are all at the back. OCR have very helpfully provided the document as a Word document.
See this post for further information.
From the University of Cambridge comes Underground Mathematics which started in 2012 as the Cambridge Mathematics Education Project (CMEP). The site provides a library of rich resources for age 16+ students with the aim of “Enabling all students to explore the connections that underpin mathematics”. Underground Mathematics is being developed by the University of Cambridge, funded by a grant from the UK Department for Education. The resources are free for all users; you can read more about the team and their philosophy here. Follow Underground Mathematics on Twitter or Facebook.
Underground Maths have given brilliant resources suggestions clearly mapped to the subject content for the new A Level. This is an Excel spreadsheet; for each content statement, Underground Maths have suggested up to three rich resources and up to three Review questions. Each suggestion is hyperlinked to take you directly to the resource on the Underground Mathematics site. Resources that are particularly good at supporting the overarching theme of Mathematical modelling have been highlighted.
These of course are suggestions. There are so many outstanding resources on Underground Maths. In our department, like many others I am sure we will be exploring the resources and bookmarking our own favourites.
You will find a growing series of pages here. An introductory post is here and you can view all posts in the category Underground Mathematics.
From STEM Learning see the A level resource package. A whole library of resources for the new specifications can be found in the collection for Pure Mathematics, Mechanics and Statistics.
FMSP A Level Problem Solving Resources
From the Further Maths Support Network
FMSP Problem Solving
FMSP Problem Solving
Nrich
Core 1 and 2 Resources 
Also from Nrich, see their Prepare for University collection.
From Jonny Griffiths try RISPS (Rich Starting Points), Open-ended investigative activities for the A Level Pure Mathematics classroom. From the home page you can download an Ebook.
Also from Jonny Griffiths his companion sites on Statistics and Carom-Maths -activities to bridge the gap between A Level and University. You can find a resource collection from Jonny Griffiths on TES Reources.
Making Statistics Vital has some tasks which could be excellent for the new specification, look at the this task on World Wide Statistics for example which includes the task with answers and a spreadsheet with data for 191 countries. Census at School is an excellent source of data.
Both MEI’s and Edexcel’s interactive schemes of work include excellent teaching notes which will help teachers decide on appropriate resources to use.
OCR have linked to some new sample MEI resources (Under External Resources). These include some very nice “problem shorts” and also the use of technology to analyse large data sets.
From MEI this curriculum mapping for their Maths Items of the month resources is a great resource.
OCR A Level Check In Test
I do like OCR’s check in tests for GCSE and I see a small number of check in tests and lesson elements on the A Level subject pages; This collection will grow.
A Level Maths A Level MEI Maths
A Level Further Maths A Level MEI Further Maths
Sign up to Edexcel’s Mathematics Emporium for some excellent resources; some of those old A Level papers could be rather useful I suspect.
Maths Challenge questions are an excellent resource at any time – not just for preparation for the competitions, particularly with the increased requirement for problem solving skills at all levels. It is possible to access Maths Challenge questions by topic for Junior, Intermediate and Senior from Dr Frosts’s wonderful website full of outstanding resources.
DrFrostMaths.com
Very conveniently it is possible to download zip files of questions by topic.
The A level mathematics working group report is a very valuable document I do believe we should always look both backwards and forwards to inform our teaching; where have our students been and where are they going?
Eduqas will not be offering AS / A Level Mathematics specifications, but note their Level 3 Statistical Problem Solving Using Software. See also the International Centre for Statistical Education (ICSE) with Plymouth University and you can follow @IntCSE on Twitter. It may be that some of the resources here will be useful for our teaching of Statistics.
Educas state: “The objective of this qualification is to assist the understanding of the problem-solving cycle of planning, collecting, processing and discussing in meaningful contexts and to use statistical software to process real data sets. It has been specifically designed to be taught in schools and colleges to equip learners aged 16-19 with a broad range of skills empowering them to successfully negotiate statistical problems in Higher Education or the world of work.”
This discovery led me to a treasure trove of resources from Educas for Mathematics at all levels, including GCSE – this definitely needs further exploration!
