If you’re studying at an International school working towards an IB, your qualifications are likely to be recognized by any university in the United Kingdom. It’s a bit of a tougher ride if you have country-specific diplomas (e.g. Italian high school diploma) and you might need a bit more research. Most universities have country specific information but often it is very unclear whether this applies to Medicine; because of how competitive it is, some universities just don’t accept anything that isn’t A-levels or IB. Thankfully, there is one very simple way to avoid disappointment in this matter! If you have “unusual” qualifications, make a generic draft of an email stating the qualification (be as specific as possible) you’re predicted to hold at the end of your high school journey and directly ask them if this is accepted by them in the run for a place in the medical school. Some universities will reply with a link to your country-specific page, some will unfortunately tell you that they do not consider your qualifications valid enough. Do this early on as admissions admin can be very slow at replying and keep a written record of everything; unfortunately, your university choice might be restricted by these answers.
N.B. Some schools will be happy to provide grading scales, to convert your qualifications into A-level grades that the universities can more easily understand, score and compare with other applicants’. If this is an option, state it in your email, or even attach the signed document.
If you don’t attend an English-speaking school or English is not your first language, don’t forget about English language requirements! All universities tend to accept a high score at the IELTS (usually at least above 7.0 in every section), but some are happy to assess your skills based on Cambridge English exams (usually a good grade at the CAE or CPE, respectively C1 or C2).