Why not try the track at CIT or UCC's track at the Mardike .
Then there are the all weather pitches attached to schools...ashton springs to mind. Drop into John Buckley's shop and ask them.
or around the grass section of the Lough
If you live in the east of the city,there is a very forgiving track in Rochestown/Mahon/Blackrock area.U can start @ Rochestown Inn,or Pairc Ui Chaoimh & the distance is anything from a couple of kms to at least 10.