This is the main place where you can get information that will help you think about Lasting Power of Attorney, Mental Capacity Act, Data Protection, What to do when somebody dies, Death Grants, Probate and much else besides. This is the generic site where you can search for your specific query.

Enter your details and get a statistical estimate of your likely lifespan.
BEWARE! Put your weight in as pounds not kilos
Actuarial calculator
This does not mean that you will each this age, or that you will retain strength and faculties but it does show what influences longevity. Having said that it does not mention that the most potent influence on living longer is to have a rich circle of friends and a full social life.

A great way into thinking about the topic of death and dying is to attend a Death Café. Yes honestly that is what they are called. They are a gathering of interested people who chat about death and dying with no imposed agenda by the host, and usually with cake. Over 15,000 have been held across the globe, many in the UK. Interested? Find out more here:

The Omega course aims to enable people to think about their future and end of life plans before they are ill. decisions should be less confusing and frightening when medical staff need to introduce such discussions.
Once someone is,ill the following organisations can be helpful.

Macmillan

Marie Curie

Age UK

Dying Matters

Cancer Research

Sue Ryder