I know of someone who recently got married and wore a petticoat under her lengha- similar to this one:
bridalslips.co.uk/_new/bridalslips/bridalstyle201.htm
Hers was from the bridal section in either frasers or debenhams. She actually took her lengha in and tried differnt types.
She was super skinny - a uk size 4 and her lengha was heavily embroided - so it just kinda "dropped" on her when she wore it. She had originally tried the hoop type skirt but it looked too weird!! So she opted for the netted one to puff out her skirt a bit. Looked nice.