So you're essentially looking for A Level related to personal finance.
You would definitely cover budgeting in A Level Accounting (
https://www.aqa.org.uk/subjects/accounting/a-level/accounting-7127/specification-at-a-glance)
However, you would also cover budgeting in business studies (see:
https://qualifications.pearson.com/content/dam/pdf/A%20Level/Business%20Studies/2015/specification-and-sample-assessment-materials/9781446914694-gce2015-a-bus-web.pdf,
https://ocr.org.uk/Images/170837-specification-accredited-a-level-gce-business-h431.pdf)
OCR's and AQA's business studies spec seem to cover more on investments and financial performance, but only OCR covers exchange rates:
https://ocr.org.uk/Images/170837-specification-accredited-a-level-gce-business-h431.pdf,
https://www.aqa.org.uk/subjects/business/as-and-a-level/business-7131-7132/subject-content/decision-making-to-improve-financial-performanceEdexcel's Economics A Level does cover interest rates, but more so about how to use it for monetary policy:
https://qualifications.pearson.com/content/dam/pdf/A%20Level/Economics/2015/specification-and-sample-assessment-materials/A_Level_Econ_A_Spec.pdfAll 3 exam boards cover exchange rates in their economics A Level
Taxation isn't covered in A Levels unfortunately.
Nothing would teach you how to save money unfortunately.
If you specifically want an A Level that would cover most of the topics, I would choose OCR's Business Studies. The topics that it won't likely cover would be in tax and possibly interest rates.
If you want something that would cover most of the topics that you mentioned (other than saving money), then I recommend doing CIMA's BA certificate:
https://myfuture.cimaglobal.com/the-cima-certificate-in-business-accounting/Unlike the A Levels, the BA certificate is a professional qualification that can allow you to become a management accountant if you wanted to.
The A Levels listed above aren't required subjects, and you can cover most of the above topics in an accounting degree. However, the accounting degree would also cover the same topics in the BA certificate, and it therefore make less sense to do it via the degree when you can just go for the certificate.
Having said the above, picking up a good book on personal finance and investments should cover most of the material that you're looking for anyway. Unless you specifically want to work in finance and/or accounting, you won't really need to go into depth on the subject or do professional qualifications in it.