Hi and welcome to the forum.

If this will be a transfer within your present company, is there any possibility of them offering an "expat package"? That could potentially include tax equalization and/or tax assistance (i.e. someone to do your UK and US taxes), home visit allowance and underwriting of some or all of your housing costs.

If you're going over on "local payroll" (i.e. without expat benefits), it's all on you - which actually has some advantages. But in that case, you may want to include something in the budget for periodic visits back to the US, especially for the wife and kids. (Some spend most of the summer school holidays back in the US - depends on family ties and traditions, I guess.) Since you will be living abroad, however, don't forget to include travel budget for holidays exploring UK and the "Continent".
Cheers,
Bev