I need to save some money?

My school is running a week-long trip to Reykjavik in Iceland. It costs roughly �800 and is running in February of 2013. I need a successful way to save up that money in the weeks coming up to it. I get �15 a week from my part-time job, and about �40 for Christmas and birthdays. I just need to know whether it's plausible and how I can keep my money safe and secure. I have a bank account, but it's quite a way away from my house, and it costs roughly �5 to get there by train and bus.