There is no connection between the kind of marriage you choose and your children’s Jewish status. If a mother is Jewish then her children are Jewish. However, some Orthodox synagogues will not accept a non-Orthodox ketubah as proof of Jewish status. Practically speaking, this means that if you or your parents were married in a Masorti synagogue, you may need to bring alternative proof of your Jewish status if you wish to join an Orthodox community. In the UK it is illegal for schools to ask for proof of applicants’ Jewish status.