given that the interview is for a branch manager position, I would say it is likely you will receive a banking case; I would therefore try to practice on cases on this topic.
As for the material for the preparation on this industry, you may want to look at the consulting club handbooks available online (eg typing consulting handbook insead) and skim for banking cases.
As for the preparation itself, you may want to follow the usual steps for case interviews, preparing on:
- Fit questions (eg Why do you want to work for our company?)
- Cases (eg Our client is a commercial bank losing money, how would you increase profits?)
- Your questions at the end for the interviewer.
In order to get advice on how to handle cases, it would be useful if you could detail the specific questions on the part of the process you need more information on.
For a pretty similar question, although related to a different sector, you can visit the following link:
Happy to help more if I can.