There are a lot of places in the school curriculum where your school could make use of resources from a number of national and international Christian organisations. Some have education departments and staff who specialise in preparing resource packs or websites for school use or train people to speak in schools.
All the major Christian aid and relief agencies produce education resources (for example, see CAFOD, Christian Aid, Tearfund, Arocha) and these resources are relevant for geography, RE and PSHE lessons. They can also be used in collective worship or as a focus for a charity fundraising event. Many Christian mission organisations are also deeply involved in aid and relief work and have useful resources for schools (for example, see The Church Mission Society, Africa Inland Mission).
Paperlesschristmas is a web-based advent resource available at www.paperlesschristmas.org.uk. It provides material suitable for class tutorial or collective worship.
Other organisations specialise in resources linked to the Bible, for example The Bible Society. The website www.crossref-it.info is a major resource for students of English literature, helping them to understand how the Bible and Christian thinking has influenced the authors of the English literature they are studying.