No Parental Accompanying Visa
First of all, U.S. immigration law does not allow parents to accompany their children to study in the United States, which means that parents cannot apply for a U.S. accompanying visa to take care of their children in the United States.
However, the U.S. has an F2 visa for the spouse and children of married international students, and the F2 visa holder cannot work or study full-time in the U.S., so he or she must provide sufficient financial proof when applying.
Parents can accompany a child up to the age of 12
Under UK law, if a child is currently under the age of 12 and has or is applying for a Child Student visa or the old Tier 4 (Child) visa, one parent can apply for a companion visa. The visa is usually granted for a period of 6 or 12 months for the first time and can be renewed after the visa expires until the student visa expires or the child reaches the age of 12 if the child has not yet reached the age of 12.
The expiry of a UK companion visa cannot be converted to another type of immigration visa and secondly the visa holder cannot work or study in the UK.