Are you a non-UK resident? Have you been working in UK or Ireland? Rest assured that under the sipp for non uk residents plan, you could transfer your pension into a UK-registered SIPP scheme as and when you desire. It has been specifically designed to cater to your specific needs of controlling your retirement savings.
If you were skeptical about your freedom to choose how and when you wish to control your investment decisions, rest assured that SIPP would provide you the option to secure your investments in the best possible way. The scheme would enable you to change your pension plan as and when you deem fit.