Greymary sounds a good idea in theory, but may not be so in practice.
1) How much is you house worth. You do not say whether you are widowed/single or divorced. If you are widowed the total tax allowance for your husband's and your estate is £635,000. Otherwise it is £325,000. Does the value of your house and savings substantially exceed these two possible IT levels?
2)You do not pay 40% on the full estate, only on the part above the Inheritance Tax allowance.
3) Many a parent has trusted their DS/DD implicitly and made the house over to them - and then sometime later ended on the street.
4) You do not say whether your son lives with you. If his home is elsewhere and you remain in the house on your own, HMRC will not recognise the transfer unless you pay your son the full market rent, with proper rental agreement etc etc, otherwise it will be treated as if the transfer is void. Can you afford to pay the market rent?
5) If your son was to become bankrupt, you cannot guarentee this will never happen, then the house will have to be sold, whether you live there or not
6) If you later need Social Care paid by the Council, they may well decide that you transferred the house to your son to avoid it being used to pay for your care and the transfer will be declared void and the house will have to be sold to fund your care. Now that Social Services have less and less money they are getting more and more keen on doing this.
7) In fact the whole idea, simple though it seems, is an absolute mine field. Take lots of legal advice from a specialist solicitor before taking a step in this direction.