Hi thanks for your question. My name is ***** ***** I can assist with this.
It loos like, from your question, that you think there might be an issue relating to age discrimination here. It seems like you think they might be treating your less favourably by requiring these tests and so on because you're almost at the "historical" retirement age.
An employer cannot treat somebody less favourably due to age unless it's possible to objectively justify it. For example, if somebody does drive machinery, and there is reason to believe that they become less able to do so as they get older, then it may be possible to justify requiring them to undertake further tests.
If, however, in your case there is no reason to believe anything has changed, as appears the case, then there is no obvious reason to suggest a test is needed, other than you're approaching 65. As such, it could be that you're being subjected to unlawful age discrimination.
If you cannot resolve matters, then you would have the right, within 3 months of them treading you less favourably (i.e. by asking you to take the test), to bring a complaint in the Employment Tribunal.
Hope this helps answer your question. If so, please do remember to rate the answer for me. If you wish to clarify any part of this answer, please let me know.