With an overnight stop may be worth looking at separate tickets if the long haul flight is cheaper ex AMS than DUB.
If travelling from the UK business class you could avoid the long haul APD by having separate tickets or a 24 hour stop over in Europe.
When making your booking you will normally have options as to the timings of the flights and you may be offered suitable flights as part of the normal booking process. Longer layovers are often cheaper as they are less popular, avoiding timings used by business men will bring savings as well. An early afternoon midweek flight is virtually guaranteed to be cheaper than the 7.00am one on Monday morning.