Just because you choose to move abroad does not necessarily mean that your estate will avoid inheritance tax (IHT). If your permanent home is abroad then it could be that your estate is only liable to pay IHT on the UK assets. The government website sets out the rules and the circumstances where you may have moved abroad, but for IHT purposes it does not count. The rules regarding domicile are complicated and you should always take advice regarding your tax position. 

The standard rate of IHT is 40% and this is charged on the value of the estate that exceeds £325,000. However, this is simplified, and this is why it is important that you take advice regarding your specific circumstances.