Thanks for the replies everyone, it's been a great help!
I was probably quite naive in thinking it would go through fairly easily given what is currently there now looks horrendous. Plus the local authority's need for affordable housing in the area! Im a newcomer to the whole self-build area and don't even own my own home yet, definitely should have sought some professional advice prior.
I am now in talks with a local planning consultant that used to work at our council as well so very familiar with policies and hopefully a way around it