Sat navs are ok , but twice on Thursday in London I did my own thing and told sat nav where to go
1st route Twickenham rugby road , to Marlborough grove SE1 ,
sat nav wanted me to go back over river to Hammersmith and go through the city and then back over Southwark bridge 
I went up the A316 then hung a right on to A205 picked up A3 to the Elephant and castle and then headed towards the A2 far easier and quicker and no congestion charge
2nd route Marlborough grove SE1 to Tilbury docks ,
Sat nav route , wanted me to double back to London bridge then pick A12/13 up in the city
I continued along A2 through Blackheath picked up A205 again took a little ferry ride up the A1020 then A13 out thus saving company 2 lots of congestion charge fees