I have a quite large expanse of lawn that leads down a slope to a stream
that moves across the garden. This winter the grass in the six yards prior
to the stream was saturated and has suffered badly. There are now quiet a
few bald patches.

As a novice gardener I'm hoping somebody can help with advice about how to
treat this situation.

Do I reseed or buy new turf? This problem is likely to occur in future so
should i be looking for any special type of grass?

I'm in the Sussex/Kent borders area and we are still getting the occasional
frost. When should I start work on this?