Hi,
I think the directions given using bus 700 will bring you near to the part of the park that leads to the Wallace learning centre. If you are going to photograph wildlife i presume you want to be on the path leading to the quarry.
It is actually quite accessible from Upper bukit timah road. If you are coming from the east one way is to take MRT to Clementi, then transfer to bus 184.
You should be alighting after the rail mall (opposite side of the road). Bus stop is at the standard chartered bank (you'll see it to your left). The bus bay different from other bus stops, with a deeper loop in. You'll also see Salvation army building and a methodist school and the trinity theological college across the road.
Cross the road and there will be a path leading in just behind the bus stop.
Other buses there are 75, 67, 961, 963, 171, 170, 178, 176.
If the directions are still unclear, you can try this website
http://gothere.sg
quite useful for directions to get from place to place via public transport, although it might not always offer the best route (but will still get there somehow)
hope you have a good time! I just went last weekend with mum and wife, but it rained while we were there...:sweat: