Cairo, Egypt to Mwanzab, Tanzania

I love the idea of travelling from Cairo to Cape and I defiantly intend to do this within the next ten years of my life. One part of it that I defiantly want to do is follow the White Nile to Lake Victoria just as the old European explorers did seeking the source of the Nile. I have looked it up and so far I know that there is a ferry from Luxor to Aswan and from Aswan to Abu Simbal and from there is one to Wadi Halfa in the Sudan. How would I go about getting from here onwards? I really want to do it via boat wherever possible. I would also be willing to do it the other way, and travel from lake Victoria down to the Mediterranean sea . Also with Cairo I know I can catch the train to Luxor but if possible I would like to take a boat to Luxor is this possible?
Can anyone offer any advice, thank you

The ferry is from Aswan in Egypt to Wadi Halfa in Sudan.

There is no ferry from Luxor or Abu Simbel. The only boats calling at Luxor and Abu Simbel are cruiseships. There are many cruiseships that travel from Luxor to Aswan, but they are very expensive. If you travel on a budget you'll end up taking the train from Luxor to Aswan.

The boats going to Abu Simbel are the cruiseships that travel on Lake Nasser, the artificial lake formed by the Aswan dam. They go from Aswan to Abu Simbel and back. Again these cruiseships are very expensive. If you are on a budget you'll end up taking a bus tour to Abu Simbel from Aswan. You leave at 4 am, go in a bus along the shore of Lake Nasser, see Abu Simbel, Philae Island, the Aswan Dam and and return to Aswan around 5 p.m.

It might be possible to hire a boat going all the way from Cairo to Aswan, but you'll have to pay several thousand pounds for it. (British pounds, not Egyptian!) It would depend upon the security situation in Luxor at the time you are going. (AFAIK feluccas from elsewhere are currently not allowed to enter Luxor.)

As for Sudan: it is very difficult to get reliable information about travelling in Sudan. Most people going this way have their own 4WD, using public transport only is unusual. I know that it is currently possible to get as far as Khartum with relative ease using buses, but apart from that ... . There are also reports and travel warnings about trouble at the Sudanese border with Kenya and Ethopia that change every few months or years. Borders open and close, best check a year before you go.