Antibiotic - a medicine or chemical that can destroy harmful bacteria in the body or limit their growth:
Antiseptic -a chemical used for preventing infection in an injury, especially by killing bacteria
As you can see, there is little difference between the two really, other than that Antispectics are a preventative measure. I.e. if i start to get a tickle in my throat, i'll use an antiseptic mouth wash to try and sto it in its tracks.
Once it is established into a throat infection, i would need to get antibiotics from the doctor to kill what is already established.
Likewise, when you cut yourself, you would use antiseptic lke savlon, germonline, dettol etc to clean the wound and kill any germs/bacteria that might have got it.
If you were unfortunate enough for the cut to get infected, the Doc would prescribe antibiotics.
In terms of your manky foot (poor you!), it would be perfectly OK to continue treating an existing problem with an antiseptic, whilst also taking antibiotics. Kind of double whammy!