I live in Lyall bay and fish around Wellington regularly. There are others on the forum who specialise in harbour fishing more than me. You can read the Wellington Fishing thread here:
Or, bookmark this link for the latest posts in the Wellington thread.
For Forecasts I use metservice and swellmap mainly. The Metservice graphs come from swell map anyway I think.
In the harbour most people launch from Evans bay or Seaview. They are both good ramps. On the south coast the best is probably owhiro bay or tarakena bay but they are not as easy as the harbour ramps.
The harbour is less effected by tide and swell than the outside coast. Southerly swell comes through the entrance and up the harbour on the east side, seatoun, scorching bay, ward island etc. Evans bay and oriental bay are usually unaffected by southerly swell. I take my kids out in evans bay if there is a southerly swell in the entrance.
Wind against tide is not such an issue in the harbour, more outside in deeper water. However, if the wind and tide are running in opposite directions the entrance will increase in chop and get rougher.
Best to aim for 10 knots or less. Look for light winds on the forecasts and try to plan your outings on those days. Always have a vhf, life jackets on, trip report with maritime radio and on the fridge.
For harbour fishing try falcon shoals, eastern side of the harbour, evans bay holes, off kau bay, scorching bay, the islands. If you want to catch fish I recommend using burley on the bottom.
Evans bay - first kingfish (released)
Eastern side of the harbour trevally
Seatoun gurnard