Retiring under a collective settlement agreement will not affect your entitlement to a top-up. Top-ups are paid on all pensions that are claimed without a rate reduction and are added on automatically by age 55 at the latest for claims in 2021. Top-ups are paid on pensions claimed at age 60 or later if the member has accrued a minimum of 20 years to their career.
Your pension will then be topped up until you reach statutory retirement age under the basic scheme, as determined by your birth year.