Can anyone offer some advice on entering New Zealand with a criminal record please?

I'm trying to find out if it is worth me visiting my dad in new zealand but am worried how my past criminal record will affect entry, last offence i have in 2001 was for possession of 0.5 grams of cannabis and before that as a juvenile a few shoplifting/theft offences, how will they affect entry or as was suggested just not inform when asked on arrival to new zealand or will that just make matters worse if my record is found? My father is offering to pay for the trip as i am on disability benefits in uk and i will be staying with him but i am worried about wasting his money if there is a high chance of being denied entry to new zealand. i am 34 years old and a uk citizen on long term benefits.