I already have to work now til 67 - my Mum retired at 60. I can't see me being much use as a teacher at 67
A big part of that difference is the increase in life expectancy between your mum's generation and yours.
Why do you feel you wouldn't be able to teach at age 67?
By way of comparison with the US, I can take a reduced government pension (Social Security Retirement Benefits) at age 62 or the full pension at age 66.5. Every year I delay raises the payout by 8% up to age 70. The SSRB isn't expected to meet your full income needs. It's expected to be complimented by a private pension or individual retirement savings. So if you save more, you can afford to take social security earlier.