4 wks in Tanzania inc work in orphanage

Hello - my name is Isaac, I am 15 and I am taking part in a trip with my school, Queen Mary's Grammar School in Walsall, to Tanzania in July 2015. I need to fund this trip and so need to raise £5000. I am going to do things like car washing, bag-packing, science tutoring, gardening, cake sales, and my little brother Asher is going to do some concerts and busking, playing his guitar, but I think that £4500 is going to be hard to raise!
The trip to Tanzania will be a once in a lifetime opportunity and I am especially looking forward to the time that we will spend in an orphanage, helping with setting up a school there. I think that this will be a chance for me and the others on the trip to really make a difference to other children's lives. I know that we are incredibly lucky and really want to help other children who are less fortunate. If I manage to raise more than the amount needed for the trip, I will give any extra to the orphanage.
Please, if you are able, help me to raise the money I need by making a donation of whatever you can. Thank you so much.