The answer to your first question is no, you do not need to consume antibiotics any longer as you have already completed the course of 3 days for Novamox and 5 days for Zostum.
Immediate implant is procedure undertaken but only when the tooth extraction was not traumatic, the extraction area is normal and no abnormality is seen after extraction, blood tests are normal, there is no previous medical history that causes harm.
There are a number of factors associated with implant placement. Everything must be kept in mind before the procedure.
Next Steps
You may get yourself examined properly before getting an implant done, then surely you can go ahead for the implant and get your normal function restored.
Health Tips
Don't rush into any procedure please look through every next step taken by your dental surgeon, your awareness regarding the same is equally important.