You can withdraw your pension from age 55. However, from 6 April 2028 this will change to age 57. The government is currently consulting on how this change might be implemented.
The consultation states that anyone with a pension in place on 11 February 2021, with the 'right' to take their benefits at an age below 57 will keep that right after 5 April 2028. This right is usually clearly defined in the scheme rules with occupational schemes, however for personal, non-occupational, pensions the right may be less clear as some pensions may refer to a set age while others may refer to normal minimum pension age (NMPA). Therefore with this type of scheme, if you decide to transfer your existing pension into a new pension the minimum age that you will be able to access your pension will change to 57 in 2028 regardless of the rights stated in the existing pension.
This is a consultation paper at the moment so things could change. However, if accessing your pension at age 55 is important to you, but you will reach this age after 6 April 2028, then you should speak to your existing provider to understand the rights around the minimum retirement age that you currently have as this could be lost once you transfer your pension