I will say ..
I feel that animals are the main thing the zoo needs for now.
The animal areas it has [or had, at the time of my last visit in 2021] are good - but I felt overall much of the zoo was devoted to non-animal 'fluff'.
@dillotest0 Not to come across as overly positive, but the zoo is extremely close to unveiling a new Reptile House, has plans to bring in ostrich later this year, has already bought in a new Komodo Dragon last month, and is currently renovating the former Reindeer enclosure and some of the empty space in the Aye-Aye house. For a zoo of its size, it has a very large animal collection, and a steadily improving one. It's far from perfect, and a shadow of its former self, but it's in a good enough state that I believe they can focus on such developments as a new entrance should finance allow for it, in my opinion.
@Panthera1981 honestly - if the old entrance and Mappins could be combined into one project... a lot of zoo developments are basically like Tetris. Buffalo's a good example, where they first built their sea lion and otter exhibits, then Rainforest Falls and finally moved their entrance before tackling their old bear grottoes and building their Arctic Edge exhibit.
@joe is correct. It will be near the gift shop, which is also on the eastern edge of the zoo. The pathway through the trees to the left of the entrance isn't part of the zoo, but is instead the Broad Walk, a major pathway in Regent's Park that spans the zoo's eastern border.