Can you wait and buy it when you arrive? YES and NO
Ok, by fire lighters I mean anything that will start a fire; matches, cigarette lighters and more specialised kit.
For cigarette lighters and matches you can certainly buy them in Uganda, and I'd recommend that's what you do. They are very cheap there, and you avoid any possible problems with airlines and their dislike of flammable liquids and things that start fires. Any small market will have plenty of sources of lighters, as will most shops.
If you want to have something a little more reliable then I strongly recommend any one of the several metallic rods that can be struck / scraped to generate sparks. These are designed to be used as fire lighters rather than cigarette lighters, creating very hot sparks to set light to tinder.
My own fire steel lives with my knife, but it's possible to buy them separately, and they are self contained, coming with a small metal scraper attached to a strong cord.
The rod is made from a mixture of metals creating an alloy that, when scraped across a rough metal edge, will produce very hot sparks- quite sufficient to set fire to tinder, cotton wool or finely shredded tissue paper. The rod can't accidentally catch fire in your rucksack (unlike some matches), it won't leak or explode (like cigarette lighters), will work even when soaking wet, and will last for years.