Dairy free margarines are available from all supermarkets, watch out though as lots do contain dairy, just check the ingredients. Unfortunately most margarines do contain palm oil, so if you want to avoid that then see our tip regarding olive oil below.
Here are some vegan margarine options:
Normal, light, and avocado, great in baking as well as for sandwiches.
Recently available in New Zealand and stocked in some supermarkets, nuttelex has a great flavour. They now also have a coconut one which is palm oil free.
Recently added product by Alfa One spreads, and this time suitable for vegans AND palm oil free! Available in some supermarkets.
As an alternative to margarine for toast and sandwiches, pour olive oil into a tub and freeze. Once frozen store in the fridge and it's now spreadable.