Although IHT kicks in at around £350k there are higher limits, approaching the £1million quoted, where residential property passing directly to children is concerned. There are also things that can be done, with no more than sensible use of wills etc, to ensure the allowances that are available are efficiently utilised.
Advice may be needed but the sort you largely can get from books and the web. few hundred in legal fees to tie it down and the job's a good 'un.
I suspect the biggest trap is people who are in long term 'common law' relationships who lack the facility to pass stuff between then entirely free of IHT.