https://crashmaths.com/a-level-practice-papers-edexcel/ https://madasmaths.com/archive_iygb_practice_papers_mp1_practice_papers.html
Edexcel have released the June 2018 papers
https://qualifications.pearson.com/en/qualifications/edexcel-a-levels/mathematics-2017.coursematerials.html#filterQuery=Pearson-UK:Category%2FExam-materials
Sample papers
AS Maths https://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2017/specification-and-sample-assesment/as-l3-mathematics-sams.pdf
AS Further Pure https://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2017/specification-and-sample-assesment/as-l3-further-mathematics-sams.pdf
Formula Book https://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2017/specification-and-sample-assesment/Pearson_Edexcel_A_Level_GCE_in_Mathematics_Formulae_Book.pdf