Definitely throw your hat in, why not?!
To emphasise some points from above -
Libraries are about way more than books, in a school library there will be journals, and audiovisual as well as e-resources.
Customer service is so very important - and you will meet a full range of humanity in a school. You really have to like people. From quiet, easy going kids to the more exuberant. There will be hormones ;) You'll be working closely with teaching staff too to ensure the library provides appropriate supporting resources for their curriculum.
You may have pupil helpers, can you give examples of staff management and appropriate delegation of tasks?
As mentioned above, IT skills are important. Just as important is information literacy - a key skill we can teach young people today is how to evaluate the resources they find on the net when researching. Books are edited, peer-reviewed, invariably accurate and factually correct (though they may still present a one-sided view of course!). The net is full of crazy people who think they know stuff about stuff...it's a critical skill to evaluate a resource to judge its reliability, credentials etc. and one which a school library will be involved in teaching.
There will be fiction as well as non-fiction. Familiarise yourself with the popular authors for the age-groups in your school.
Know your alphabet (you'd be surprised!) and have a look to see how non-fiction files in your local library - many schools use a simplified Dewey (there will almost certainly be shelving tests).
I wouldn't be surprised if in a school library interview you would be asked about child safeguarding...
As an assistant you shouldn't be responsible for leading on any of the above. There should be a librarian or teacher librarian. I'm delighted to see some schools still advertising such posts as cuts have decimated library staff in schools.
Sorry, very quick answer as I'm doing bedtime! I'm a librarian who had close relationships with our schools library service when I was in public libraries.
Best of luck :)