I did find it a bit strange that nothing has appeared on the Council Planning Portal for this. The loft conversion is permitted development but it still should be processed through there and the side return should also be on there.
Why would permitted development appear on the planning portal? Only if someone's applying for lawful development certificate I'd have thought.
It should have building control app but don't think planning portal holds all of them.
This. You can apply for a certificate of lawfulness after the fact under PD. Building control can also be done privately via an approved inspector which I don't believe will be registered on the local authority website.
I did find it a bit strange that nothing has appeared on the Council Planning Portal for this. The loft conversion is permitted development but it still should be processed through there and the side return should also be on there.