There is a helpful website at www.teacherspensions.co.uk that provides comprehensive advice on the Teachers' Pension Scheme. They state that "if you are applying for actuarially reduced benefits (ARB) and you are in pensionable employment you must leave such employment with the consent of your employer to gain immediate access to your retirement benefits.
Employers cannot, however, withhold their consent for longer than six months from the date on which you request to leave. ARBs are paid from the day after the last day of pensionable employment. However, if you are not in pensionable employment, ARBs are paid from a date not earlier than six weeks after the date of the application". There still seems to be time to retire under these provisions this summer without your employer being able to withhold their consent.