While LPF has wonderful views and makes a pleasant spot for lunch - it is hardly a substitute for La Colombe in terms of the quality of the food.
Other closer options might be - Catherina's at Steenberg where I had a really excellent dinner last week. They also have a new bistro attached to the tasting room which is prooving very popular and worth a look.
The River Cafe at Constantia Uitsig has been taken over by La Colombe's chef Luke and again initial reports have been very good, also worthy of consideration.
I also always think Buitenverwachting is a good choice for a pleasant lunch in the Constantia wine valley.