Ive been in USA since Jan 5th 2013, I am going to file a tax return, I pay two mortgages in the UK, this does come out of my USA salary, can I claim back the tax on this, what about dependable children who still live in the UK with there mother, My ex wife.

Whether you can deduct, on your US federal income tax return, mortgage payments on foreign property is a good question. I suggest you review the URS bulletins on the subject which are available online. Are the properties your principal residence, or are they rental properties of yours? If not, it is doubtful that you would be able to deduct them in any event.

I don't believe you can claim your children as dependents. I believe they would have to spend at least half of the year with you in order for you to do so.