Depending how old u are, if u are a young women they only usually happen once a month wen ur on ur period. If ur 50+ u get them alot. I would suggest going to the doctors as they can give u some good advice on tablets/herbal remedies to use to help.
Wear some skinny jeans or jeggings with some ugg style boots, or some gorgeous ankle boots, and a long top with a cardigan. Wear ur hair down as it will make u slightly warmer and some thick eyeliner, but not too much make up.
A lot of celebs started out as models. Vernon Kay was a model before he became a radio/tv presenter. So i would say go for it, if u got nothing to lose then just do it and if u eventually decide its not for u, then u can always quit.
Chocolate! lol, sounds silly, but it really helps. Its a relaxant and helps the hormones wen ur due or are on urr period. If you dont like chocolate, anything sweet helps!