Another benefit of travelling during April is that you will be able to experience the Wonder of the World, Victoria Falls, in full flow. Thanks to the long rainy season, the water levels in the Zambezi are high, so the current and spray of the falls will be powerfully surging over the edge. At this time of year it is best to get above the falls so you can witness the whole scene without your photographs being overwhelmed by the spray.
As this is not the optimum season for wildlife watching in Zimbabwe the parks are likely to be quite quiet and rate will be lower than peak season (July to October).