Is Duty a given when shipping your personal belongings?

I moved to the UK in late 2013.  I brought with me what would fit in my suitcase.  A few weeks later I returned for a family emergency and was there for a month and brought back two suitcases of mostly family photos. Yes, I have that many.  Anyway, I've been here nearly 1.5 years.  I still have a fair amount of stuff to ship over that I didn't have the money to ship earlier on.  When I go over this summer I plan to sort it and figure out what I don't want to live without.

My question is will duty be due on it?  Is there a limit on it?  I'm wondering if I'm going to have to cull it down to a very small amount and learn to live without all those little things I'd have brought over. 

Also I'm a fanatic genealogist and have probably two boxes of research and old family papers like tax forms and old property titles.  How would I go about describing that for the paperwork?  From what I've read they want a description of every item.

Thanks, Snowdonia

We shipped most of our stuff using UPack-WeShip we had no duty to pay as it was all personal items and over 6 months old.  We too had all our family tree paperwork that we collected over years of research.  We listed it as "Family Records" on the shipping list and we had no issues.

The information and forms you need can be found here, I think:
https://www.gov.uk/moving-to-uk