Rosemoon wrote:I would like to try but I m in my early 30s... Would it b an issue? Can anyone pls help... Thanks!

If you do not look like you're in your 30s then maybe? However, like someone said earlier, why would they hire someone in their 30s if they can hire someone who's 18 or 21?
If you google "Singapore Girl", there will be many sites stating the it is SIA's icon. The flight stewardesses are supposed to be young and fresh. You can't compare it with BA. The trademark of SIA is the Singapore Girl. If you think you can offer them what an 18 year old can offer, then go ahead.
However, to prepare you for the worst, I highly doubt so - in the first round of group interview, you'll be asked to introduce yourself. There will be many young girls there and when you introduce yourself amongst them, they will definitely compare you with the group.