He should be more concerned about the Israelis conspiring with the Kenyans and Tanzanians than the Brits (who had already lost their influence / were unlikely to regain it).
Post 1973 oil crisis Britain isn't going to do anything like that with Israel.
Idi Amin was a Muslim. If the British co operate with Israel openly against a muslim ruler then Britain would jeopordise their markets in the newly wealthy gulf states.