Where can I find Cat litter in Heathrow?

Cat litter can also be found in these cities:

Borehamwood Brentford Byfleet Epsom Feltham Greenford London Ruislip Slough Walton-on-Thames Watford West Drayton Woking invalidcity

You can also find this in Heathrow:

Cat Flaps Hay Bedding Bowls Pet Food Pet Food Wood Shavings Chews Straw