prenups, postnups, wills or trust

Hello-
I am looking for general and accurate information about prenups, postnups, wills, trusts and the like.
From reading another thread- it seems that a prenup drawn up in the USA will not be vaild in the UK?
Not that we have time for one, anyhow- but I am still curious!

I am American, marrying my Brit in one week!!! 
I will be moving to UK in January...   

We want to make sure that we are both protected and that his daughter's future will also be protected.
Then we won't have to have the fear looming in the back of our minds-
we can just enjoy our life together.

Do postnups, drawn up in the UK once I move there, bear much weight in court?
would it be best to do a will?

Should we just put aside a trust for his daughter?

I want to include his daughter in my will as well, as I do not have any children of my own, nor do I plan to have any. She will be just perfect for me! 

Thanks in advance for any insight!