I would recommend you look at the Lloyds website to give you an idea as to what type of products they offer.
As a Personal Banker, you will be dealing with account queries, setting up new accounts, loans, general insurance and providing leads to their mortgage and financial advisers.
In the intereview they will be looking for experiences that you have had dealing with people face to face, siuations where you have had to deal with a difficult customer or situation...what the problem was, what you did to satisfy/resolve the situation and what the outcome was.
Situations where you have deivered exceptional service....
How you plan to achieve your targets..adn if you ever fall behind your target...what would you do to catch up...
How much of a team player you are and give examples...
They may also ask you do carry out a straight forward english and maths test...but dont worry too much about these...you should be able to do it with your eyes shut..!!
Hope this helps.......good luck