Accountancy is a profession that does not necessitate you be a graduate in order to go into the field. Most companies offer various school-leavers programmes and others may provide you with the AAT qualification before they put you through the ACA or ICAEW.
What does this tell us? It tells us that not only is Accounting at A-Level not at all a prerequisite to Accounting and Finance at university, but it also tells us that Accounting and Finance is not a prerequisite to being an accountant.
If you are unsure on becoming an accountant, it might be best if you did another social or physical science (physics, maths, economics) before making your mind up. If you have brilliant AS/A level grades and definitely want to become an accountant, then you may wish to look at various non-graduate entry routes in other to save yourself £30,000 worth of debt and get earning quicker.
And this is from someone who has applied for A&F this year.