Hi there,
I was considering this too! However, I think it's wise to just try your best and get in here. Firstly because of the fees for international students being very high. Secondly, you have to do an admissions test which is very different to the UKCAT/BMAT. Thirdly, are your job prospects as good (if you come back to the UK, you'd have to take a year or two out sitting English exams in order to practice medicine here in the UK)?
If you don't get in first time round in the UK, there's nothing stopping you from reapplying year after year. I'd say that if it gets to your third attempt, consider international universities.
Be privileged you're studying in the UK, international students are dying to come here!