sounds good mate, nitrates really shouldn't be off the scale tho. Stop adding ammonia and do a 40-50% water change every day to bring the nitrate level down.

Don't add too many fish at once. A 120 litre tank is a good size, but start off with no more than about 5 small fish for a week or so, then add a few more.

Have a look over on www.fishforums.net for some good info