Interpet aquariums are usually found in Pets at Home, and they offer really good value for money.
You can use the Interpet Fish Pod Glass Aquarium - Fish Pod 48 Litre for tropical and coldwater fish. You get everything you need from heater to filtration which is done in the hood of the aquarium.
You even get some tap safe you can setup your fish tank straight away, although we recommend waiting at least 1 week before adding fish.
These really are neat little fish tanks and ideal for kids and adults a like, ideally placed in a neat little corner of the room.