Consider your costs and budget very carefully, not just camp fees and flights. You may need to cover things like: 1. International travel costs 2. UK travel costs (station / airport to Kelmarsh and back) 3. Visas 4. Travel costs to visa interviews 5. Passports for your group members 6. Medical and/or travel insurance 7. Extra spending money for food and drinks during the journey, souvenirs or other extras.
Why not share your best fundraising ideas with the UK / international delegations you are camping with? Working on a shared target like this will give you all a common purpose for the whole year! Email email@example.com if you have not yet been matched with another group.