Check out forums and ask your friends to figure out what type of test a specific firm uses - look on The Student Room and Wall Street Oasis.

https://www.jobtestprep.co.uk/banking-employers

https://www.practiceaptitudetests.com/industry/banking/

https://www.how2become.com/online-bankers-test/

https://www.graduatesfirst.com/

Through your St Andrews login you get free access to Graduates First: https://www.graduatesfirst.com/university-career-services/standrews

Psychometric tests are the least predictable part of your application and the stage at which some of the best candidates fail. They require long-term preparation to succeed, and a level of effort that most aren’t willing to put in. I would recommend preparing thoroughly for the roles that you really want. Preparation for one firm transfers well to all other firms. Within an industry, most psychometric tests are similar.

There is no way to prepare for these tests other than practice. If you can, purchase test prep material for the firms that you really want to work at. A healthy salary will be worth this small investment.

Examples of tests:

Quantitative/ Mathematical - most common for investment banking and consulting

Verbal/critical reasoning

Non-verbal reasoning/ logical

Situational judgement - work-based scenarios