You are leaving a flower bed, aren't you? As long as you drain into it then you wont need PP. Unless you are on a load of clay this will drain OK one would imagine.
Drain an entire drive into a flower bed
You are kidding?
The bed is large enough to easily accommodate 2 cubic metres of soakaway, providing it will soak away and not just pond, which I plan to test.
Installing drainage might well be expensive, as there's no downpipe on our land, as I said before.
I suppose I could test it by covering the garden in tarpaulin and seeing what happens to all the water!