My ears were burning! :-) (See later comment in thread re: scammers and mystery teachers.)
The name is British International School Classic, or BIS Classic for short.
It is a private school with primary and secondary age pupils.
Not all classes are taught in English, but many are. In fact, I'd guess most were taught in Bulgarian. However, there is a big emphasis on English speaking, and the goal is to get students up to CEFR B2 level as soon as possible (but certainly before leaving). Plus, of course, a second foreign language (Chinese, German, Spanish, French). As you'd expect, there are classes to help expats learn Bulgarian.
As a quick estimate, I'd say 85% of students are Bulgarian, and 15% are from expat families.
The Principal is Miss Reni (Reni LLieva). She's always happy to discuss with parents of potential students.
https://www.classicschool.org/en/staff
Curriculum is Bulgarian standard, plus some IGCSEs. The school was recently approved as an International Baccalaureate school, and is now offering the IB Diploma, a well-recognized international qualification.
Fees are very reasonable by Bulgarian standards, and quite surprising by international standards!
There are many students - as you'd expect in a private school - from wealthy Bulgarian families. So perhaps the worst I can say is that a few are a little self-entitled, but that happens in many private schools. However, in general, very nice students with good level of English, and helpful and supportive staff.
I am a real person, but I do have a bit of a "portfolio" career, as I'm a former software engineer & software entrepreneur and I still work (when I can) with early-stage tech ventures. However (as per my Linkedin profile) I have been teaching and tutoring for almost 20 years (albeit as my second career).
I have been in Plovdiv since 2018, and I started teaching at BIS Classic in 2019. My subjects (but I don't teach all at BIS Classic) are Mathematics, Business Studies, IT/ICT (without software engineering), and Computer Science (with software engineering). I have a master's degree in Computer Science, and an MBA from a top-ranked business school. I started (but, sadly, didn't finish) my PhD in Management Research at the University of Oxford. I also have my PGCE in Secondary Mathematics, and the IB teaching certificate for Computer Science. There are many other excellent, well-qualified teachers on the staff, including those with an expat background who have returned to Bulgaria.
So... I'm legit... the school's legit... the students are legit. :-)
And I'll tell Ms. Reni that we need to do better on the website! :-)