2. I lost all interest and legal is English based but I like maths more and not a very good English student 
Don't worry, I totally understand. I am exactly the same. I wasn't a very good English student at school either. Much preferred technical subjects like Maths and IT

(to this day I still don't like English, perhaps this is why I am not becoming an English teacher...)
Anyway - only you will know what path to take. Get some thoughts on both Physics and General, read a textbook or two (to get an idea about the content) and make a decision. I'm sure you'll make the right decision for your future aspirations

In terms of general/further: It is okay for general - but if you plan on doing Further in Year 12, you need to be aware that whilst the content is perceived to be 'easy', a few marks lost can make a significant difference to your overall score (in the exams), due to the intense competition. Why is this the case? 'Easy' content has its downside.... your ATAR/SS's are based on ranks, not actual scores.
Cannot really comment on Physics since I have had no experience with it. Hopefully someone else can fill the gap.