Hi Walnut.

yourboi could look up the old spec, there may be some relevant questions.

yourboi could buy some CGP Exam Practice Workbooks off Amazon.

yourboi could try REVISE Edexcel GCSE (9-1) Combined Science Higher Practice Papers Plus: for the 2016 qualifications (Revise Edexcel GCSE Science 16) https://www.amazon.co.uk/dp/1292211083/ref=cm_sw_r_cp_apa_8COZAbE7GXZ18 lad.

There are these for your Maths:

New GCSE Maths Edexcel Practice Papers: Higher - for the Grade 9-1 Course (CGP GCSE Maths 9-1 Revision) https://www.amazon.co.uk/dp/1782946594/ref=cm_sw_r_cp_apa_tEOZAb3R91X63

Edexcel GCSE Maths Higher Practice Test Papers (Letts GCSE 9-1 Revision Success) https://www.amazon.co.uk/dp/0008276129/ref=cm_sw_r_cp_apa_0EOZAbM7TTPGX

Honestly there are tons of stuff:

Google

Edexcel 9-1 [subject] exam practice OR practice papers