Yes. From most of the SWT area, London Terminals includes all of Victoria, Vauxhall, Waterloo, Waterloo East, Charing Cross, Blackfriars, Cannon St, London Bridge and City Thameslink. On the Weymouth line you may also use Paddington.
Your ticket will be returned at Waterloo to allow for this onward use. However in my experience it may not work the Waterloo East barriers.
It would not cover LU transfer, however this would be a pointless exercise really, as the walk around the underground passageways at both stations (and any time on the tube) is almost certainly significantly longer than walking over the bridge between Waterloo and Waterloo East, which should really be considered parts of the same complex, (although they have separate gatelines.