In reply to An Triubhas:
Of course, I have a question:
What makes you convinced that a trip to Kili is the most effective way to raise money for this particular charity?
As has been said, if your main objective is to raise funds for a given charity, there are lots of other ways to achieve this, many of which do not involve the time and expense of getting a Westerner to Africa and then up Kili.
One effective way is to persuade people of the value of the charity. Encourage folks to get involved as volunteers themselves. This way people will see the sense of the work for themselves, and the number of donors (and fund raisers) will increase.
Or you can devote time and effort looking through the various grant awarding bodies. See what funding might be out there looking for a home.
You can mix fund-raising with campaigning. For example, there has been a recent campaign to live on a pound a day.
https://www.livebelowtheline.com/uk This was a mix of experiential learning, campaigning and fund-raising. I think it was done very well. I know other people who have got together and created a "shanty town" on the local high street for a night to raise awareness of street poverty round the world. Those who took part gave the money they would normally spend on a Friday night to a charity like Shelter or Oxfam, plus they asked for donations, made "gifts" out of "junk" just as some street people do in other countries, so campaigning, raising awareness, involvement and fund raising were all mixed in.
To me these are all much more effective ways of raising money and promoting the work of the charity than any sponsored trip up a mountain or along a trek.
Of course, my suggestions only work of the charity is worthwhile...