Click to read the Editors’ Code of Practice (valid from 1 January 2016)
And the Ofcom Broadcasting Code
The BBC has additional rules under its extensive Editorial Guidelines
The BBC is now regulated by Ofcom but operates to its own guidelines, which include the whole of the Ofcom code but go much further. The guidelines website also has some commentary and guidance to explain its rules, which can be useful (and you can cite it in an essay).
In particular, have a look at the Mandatory Referrals under each heading (Accuracy, Harm and Offence, etc). These highlight situations in which journalists and programme makers may wish to breach the usual guidelines in the public interest, in which case special permission must be sought within the BBC.
Both the Ofcom and BBC sites feature regular updates on developments and discussions relating to media ethics.