Not sure about heavy wetter day nappies, but for night time we use either slinki minkis or standard minkis, both made by "nappies by minki". They're basically very roomy, fleece outer pockets with more than enough room for any amount of absorbancy. There are also a lot of dedicated night nappies that lots of people on here use, I'm sure someone else will be along shortly with more advice
I agree with Vicki about the monkeyfoot wetbags, they come in some huge sizes and are great to hang on the buggy on a day out, and they look very pretty too, so you're not stuck with some horrible utilitarian looking bag.
Are you in Ireland? Whereabouts? There's a few others of us here too, I'm in Dublin
Look forward to talking to you.