Looking at the 1881 census, it seems they probably married either in Kent, or possibly in Cornwall/Devon or Swansea - these are all places where John, a shipwright, could have been working.
Phillips is difficult! Especially with names John and Elizabeth - I'd suggest getting the birth certificate of one of the children, that would give you her maiden name - then finding the marriage, hopefully she's not Elizabeth Smith, Brown, or Williams!
Any idea of what John's middle name might be?