SATs are more of an equivalent to GCSE if anything, so don't pin everything on that. They'll still look at your A levels, along with taking very strong consideration of your teacher reports from school and looking at extra curriculars, essay most likely (not too sure about Berkeley specifically) and other factors.
But as I say, A levels are still important and Berekley isn't a piece of cake to get into, it's not somewhere which would best be described as a 'backup plan'!**