For most of the walk we will follow the Wandle Trail. We will pass historic water mills, walk through nature reserves and Morden Hall Park to reach Grove Park in Carshalton. We will have a late lunch in one of the cafes or a picnic before climbing up to Carshalton Park and finishing the walk at Carshalton Beeches.
Colliers Wood is on the Northern line, Carshalton (for drop out) and Carshalton Beeches have regular trains back into London (Victoria, Farringdon) and it's all covered by Oyster card.
There is a Sainsbury's with toilets near Colliers Wood station and there are more toilets along the route.