Hi jiba and welcome to the fishroom. A couple of bristlenoses would be ideal for your tank. They look like plecostomuses (plecostomi?) but, unlike the plecs which grow over 30cm, the bristlenoses (Ancistrus sp) only get to about 10cm. They are very peaceful and help keep certain types of algae down.
Try and avoid the algae eaters commonly sold as Chinese Algae Eaters as they can harrass other fish. Siamese Algae Eaters will get a bit territorial as they grow.
If you just wanted some bottom dwellers, not ones to particularly eat algae, there is a wide range of corydoras species available. These are in the shops under various names such as peppered cat, bronze cory, albino cory etc.
I suggest you get in touch with the Waikato Aquarium Society as they can be a lot of help to you (and possibly a source of cheap fish and plants). Rob, in this forum, is a member or Dave (also here) can also get you in touch with the right people.