Hi there
Think you need to take it one step at a time :P :P
Firstly, not being married is not a problem. If you can prove that you have been in a relationship for more than one year (ie. bills, joint accounts, council tax etc..) then your classed as whats known as a 'Defacto Relationship' which is fine
I came up against this as we are not married, but it caused no problems
As for the kids thing, you maybe need some good advice on that one.....
Good luck
