Hi!
Your chances will be really high if you can demonstrate a well rounded personality, but you must also be academically sound and be declared able to meet their typical offers by your school (your predicted grades should be no less than their typical offer) to be considered. You will be guaranteed accommodation for the first year at UCL but I think you may need to find your own place to rent for the second year onwards. I'm not sure how business related departments operate but it's usually the case that you you apply through UCAS, send in your personal statement, references and predicted grades, get interviewed if you've passed the preliminary consideration stages, receive an offer and then all you need to do is meet their offer to be accepted. Since you're abroad, they might not call you in for an interview and they might try to coordinate a Skype interview (or similar) instead. You might not be interviewed at all, but it's best that you try and prepare by doing mock interviews so that you're on comfortable grounds when being interviewed.
I hope I helped you with your questions. I'd like to make you aware of something regarding your tuition fees, in case you weren't aware of it. Should you be accepted to study in the UK, you might be charged international fees because you might be classified an international student, having not resided in the UK for 3 years prior to the start of your course, despite being a Briton. You have to be very careful because international fees increase year on year and are significantly higher than the fees that 'Home students' pay (£9,000). Students who have resided in the UK for 3 years prior to the start of their course will be classed Home students, regardless of their nationality, if the main purpose of their residence in the UK during that time was not to receive full-time education (i.e. they normally live in the UK, so that if they weren't studying, they'd still be in the UK because they live here). This might mean that you will be charged international fees, unless you appeal their decisions and prove that you were out of the UK on a temporary basis (i.e. because of you parents' work, etc...), and so you must show them that you have maintained connection with / assets in the UK (so if you have not sold your house, not closed your bank account, etc.. then you might be able to prove to them that you were out of the UK temporarily).
The reason I brought that up is because I had assumed that I'll be paying home fees (£9,000) when I was abroad due to my father's work but when his work contract expired and we returned to the UK in time for my A-levels (2 years before starting university), I was classed as an international student when I applied, simply because I had not resided here for 3 straight years prior to the start of the course, despite having been here before my father went for work, and despite being a British citizen. I then appealed and proved to UCL that I was abroad on a temporary basis and so they changed my status to a home student after processing my appeal. So you should not assume that you'll be paying home fees and should be prepared to pay international fees, and I felt that you should know this before committing yourself 100% and before you plan all your finances.
Best of luck!