OK Letting agents are below estate agents in the list of people you would trust, somewhere next to crack heads.
The make money on initial rent out and monthly (you will need to do this unless you can field calls from the tenant while away), I have known of some that try and juggle their existing clients into new homes to get more finders fees (normally 50% of the monthly rent)
Make sure they are part of the Ombudsman scheme, ask to see their inventories, double check, take photos’s, give them a copy ask them to sign for it as the state of the property that you hand to them.
Do not expect the house back as you found it, expect it to cost you money.
If you start from this point you won’t feel disappointed.
On the plus side some are better, more like excessive weed smokers in suits.