@Jason64 maybe some LL training specific to Wales would be a good idea.
A starting point would be reading all of the guidance at Renting from a private landlord | Sub-topic | GOV.WALES
There’s a previous link Contract Holder Notice WALES!
saying
what you’ll need according to the thread is provide a written statement of terms within 14 days - pretty sure there will be templates available online for this but the contract itself may contain most of the detail.. It says OR were going to provide guidance. Check with OR support or DM @Dan4 .
This seems most unlikely- not mentioned as a reason an s173 could be invalid by Shelter cymru
And not mentioned in the wales gov flowchart as a reason why a s173 would be invalid
Source: gov.wales Issuing a valid landlord’s notice under section 173: flowchart | GOV.WALES
But again you could also check with OR support/ @Dan4
Best