The self-employed get no auto-enrolment and no employer contribution, so a personal pension or SIPP is the main route. Your provider adds 20% basic-rate tax relief automatically; higher-rate taxpayers must claim the extra 20% through Self Assessment. You can contribute up to GBP 60,000 a year, capped at 100% of your earnings.
Auto-enrolment - Does not apply. There is no employer to enrol you and no employer contribution to...
Personal pension / SIPP - Relief at source: your provider adds 20% basic-rate relief automatically....
Higher-rate relief (40% taxpayer) - You only get 20% automatically. Claim the extra 20% on income...
Additional-rate relief (45% taxpayer) - Claim a further 25% (on top of the automatic 20%) on income...
Plus 5 more in the full guide

freedomisntfree.co.uk/guides/self-employed-pension-uk