The banks can only have 15% of their total mortgage lending above 80% for non-first time buyers (LTV rule). If you don't need an exception to the LTI rule, it doesn't mean you will automatically get an exception to the LTV rule - it makes it possible, but you still need to be one of the 15% of people who gets approved for the exception.
If you really need the LTV exception, the solution is to shop around until you get approved for it, starting with the best option for you (rate, term, other features). If that bank doesn't approve you, move down the chain until you either get approved for what you need, or have to accept the 20% deposit requirement, if you cannot get the exception. The banks treat second properties very differently, so that may have a large impact on your chances as well.
Best Regards,
Dave Curry, Irish Mortgage Corporation
https://ie.linkedin.com/in/davecurryirl