SIPPs are a more flexible type of personal pension whereby plan-holders are able to invest in a much wider range of investments and therein not restricted to those offered by one single insurance company, mutual fund manager or bank.
SIPP holders can begin taking benefits at any time between age 55 and 75. Any residual fund can be passed to your beneficiaries tax free on your demise up to the age of 75. After that time, they will pay tax at their marginal rate of income tax.