Moving to London from USA

Hello,

I am looking for advice on an idea that my partner and I have had about leaving the US and moving to London. He works for a company in Tampa Florida that had an office in London that he would be able to transfer to. We are have moved from the west cost of the US to the east cost and now we are looking at leaving the country all together. We have little information on how to start this type of move. We are looking at about five years to put ourselves in a place to make this move. We would like anyone that has made this type of move or had knowledge about it to please give us your recommendations on things that we should look into or consider during this time. He works in the insurance industry and I am changing from the the IT industry into the medical field at this time.

Any recommendation would be great,
Thanks
David