Just one bit of advice if you're going to send your maid to the wet market or any other errand: tell her what time she must be back at your house. My friend's maid would go for as long as 3 hours - and often return without some of the basic things she was sent out to buy! It turned out that she was going elsewhere to visit her friends and to meet her boyfriend. I would accompany the maid the first time so you are both clear on how to get there (eg. which bus you have to get), and also so you and she are aware of the quality of the produce, and the type of things you prefer. You can then work out how much time is adequate for her to do the shopping.
PS - you will find markets at HDB blocks - there is one in Clementi, near the cinema.
Suggest you read "Culture Shock - A wife's guide" by Robin Pascoe. She addresses this problem - and recommends from experience that you do the errands yourself and not send your maid!
