It sounds to me like you’ve gotten things pretty well sorted! I think whilst you’re still completing your A-levels, the most important thing is to keep up-to-date with legal news and happenings, through newspapers, online legal news sources e.g. Legal Cheek, The Law Society Gazette, the Law section of The Guardian.
The fact you have an internship is great as well! Make sure you make the most of it by asking lots of questions and trying to get a feel for the firm, the area of law they practise in and why you enjoyed it – that will come in handy in future interviews.
Just keep applying for these sorts of opportunities, keep completing work experience and internships in firms and keep up the enthusiasm – university will bring a whole lot more opportunities.
I hope this helps – let me know if you have any further questions!