In general, if you are under 5ft 7ins tall, then it is unlikely you will make an impact in the world of catwalk modelling in the current obsession with tall,stick thin models.
To undertake catalogue modelling, the parameters are slightly less stringent, but nevertheless
you would still need a figure that shows the garment you are modelling in the best possible light, therefore if you are overweight or have a bust size out of proportion to the rest of your body shape
then you will struggle to find work in this category.
Regarding glamour work,you have a wider range of body shapes and facial appearences as you are showing off your own body and not necessarily modelling a particular item of clothing, so whether you are a size 8 or larger it is not necessarily so important