(advice for England/Wales)
stop worrying because your deposit is protected. (If it wasn't, you could sue for it).
All those threats can be ignored, the agents don't have a legal leg to stand on. Ignore the bollocks being talked by 'people'. Rachman has been dead over half a century and while deposit protection has only been in since 2007, it covers all your concerns.
Also forget 'I heard' which always leads to bollocks. Look on gov.uk or the Shelter site for simple statements of tenant's rights. It's not a struggle.
Give your formal notice in writing (not text, not email, writing) a month before the end of tenancy. By the end of tenancy, you and all your stuff need to be out. Leave things clean (so someone else could move in without cleaning up) but no, of course you don't have to repaint. Return the keys, read the meters, contact the council and utility suppliers to terminate your accounts, have your mail forwarding set up. Be there for the checkout. If no inventory, landlord has no rights for deductions. Take your own photos, keep in touch with the deposit scheme and inform yourself on the dispute process.
remember agents are not regulated so be informed.
(if you are still in a fixed term, check your lease for break clauses. If you are on a rolling tenancy, give a month's notice to expire on rent payment day)
The property needs to be in the condition you found it, LESS (repeat LESS) wear and tear. If it was newly decorated and recarpeted the day you moved in, the landlord would still be expected to replace carpets and repaint. None of it has any value after 7 years. If you have damaged anything, the deposit deduction is pro-rated against the age of the item and still equates to flumpence ha'penny.