I have no inside knowledge, but looking at the park as it is, and the phase 1 plans, there is an awful lot of work to do to create the New Bristol Zoo. The acreage appears to be the same as Chester, but the current holding of mammals and birds is tiny.
The proposal indicates an increase of parking to 1800 vehicles, using the same entrance close to the M5 junction. A busy morning influx of visitors I can imagine backing up to the M5. I assume they have thought of this, or they will have to move the entrance further from the main road.(as Chester had to). For such a major increase in visitors, there will have to be major infrastructure improvements on pathways, toilet provision,catering etc. Not to mention the construction of enclosures. I can imagine 10 years plus of continuous development, assuming they have enough investment.