Offline map of London underground train
1. London Tube Map (zoom in, zoom out)
2. Index to stations

Online travel plan - Transport for London (tfl) with:
Tube, DLR, Tram, London Overground, Coach, Bus, River Bus, National Rail
3. Plan a journey in London with tfl.gov.uk
4. London BBC Weather

You can use the Tube map offline , but to plan a journey you need to be online.