I don't have a westie but I have the experience in taking care of them..
Westies are classified under the small breeds category so technically, they're HDB approved. However, they can be quite destructive at home if not given enough exercise. Walking the dog daily would just do the trick.

Anyway, if you're planning the buy a westie, be sure to check out the parentage and where you purchase the dog. Westies tend to have heart problems. A friend of mine bought a westie with grade 6 heart murmur. In other words, the dog could die at any time. We took the dog to three different vets for their opinions on the matter and they all had the same diagnosis. It's quite heart wrenching really.