We have Ukrainian men getting their women and children safely to the Polish and other borders, and then going back to fight for their country.
On the other hand have mainly Young refugee men crossing the Channel by boat claiming asylum from war torn countries.
Is it in their culture that the women and children fight for their country?
A) you're assuming that other refugees are fleeing from war. That might not be the case, there's hunger, famine, persecution, lack of prospects, and other issues besides war that causes refugees.
B) Ukraine has invoked martial law, which requires men of the right age to be conscripted, which prevents young men leaving. Other countries, such as Yemen, Sudan, etc, do not have the governmental infrastructure to organise such conscription, nor to prevent others leaving.
C) The war that might be raging in other countries may not be a war that many want to be involved in.
D) Many young men do not have 'families, wives, and children' but they are the last hope for their dependent parents/grandparents, etc, to continue the family name.
You're obviously ignoring many such issues to form your usual bigoted opinion.
A clear case of forming your prejudice then looking for some facts to support it.