Too far to be a practical journey by bus. Go by train from Clapham Junction to Waterloo. Cross the road to Waterloo East Station and take another train to Woolwich. They are frequent. Oyster Cards are valid for this journey
www.nationalrail.co.uk
There is no bus that goes direct from one to the other. You can get the 177 to Peckham and then the 37 or 345 to Clapham Junction. It is 12 miles driving though.
