I don't like the sBMJ. It is neither British nor Student. Most of it seems to be written by Spanish registrars. I've nothing against people from abroad or qualified doctors contributing... but the sBMJ is not an international scholarly journal, it is a specifically a journal for British medical students so they should contribute most of the material. Otherwise I can read the actual BMJ for better quality content.
Incidentally a lot of BMJ content is free online. I think the most recent issue, all issues older than a year and all research papers. Or something like that. Obviously, a lot of it (most) will be incomprehensible to me, let a lone if you'er in L6, but all the same you can just go and pick out what you like.
There's also a Student Medical Newspaper. I've never read it though and never heard it mentioned...
Medical Student Newspaper - The UK's biggest free medical publication