Why are you asking if you can still be sacked, has something else happened since? Or do you mean can they sack you for being off sick? The answer to that is yes they possibly can. Most employment contracts will have a clause allowing the employer to terminate if the employee has a poor attendance record (which would include sickness).
So, yes, you can possibly be sacked for being off sick and whilst off sick.
If you haven't already, start looking for another job. They obviously think your not worth it and it is only a matter of time before you do something that will allow them to get rid of you.
I would suspect that if your reinstatement due to the tribunal has included continuity of emplotment they are now going about it the right way and will go by the book (if they have any brains) and get rid of you.
A has been said being off sick does not bar you from being sacked or made redundant.
Agree with previous answers. If you haven't got a copy you need to see policies relating to absence/attendance management and this should clarify where you are on the procedure and the possible options - one of which will probably be dismissal.