I need a route planner

hello! Another week to go, and I will be in London, having the time of my life with some very good friends of mine. We will be seeing everything both during the day and at night. Most likely, the train and tube will be our primary form of transport. As London is apparently a huge place, we might benefit from planning our route in advance to avoid getting lost too often. Where can I find a route planner, please?

There several websites that will be of assistance to you in this case. Like http://www.nationalrail.co.uk/ for instance. The only downside is that it provides only the train times and routes, and nothing for the underground. For that, you will have better luck with the Transport for London site, which you can find at http://journeyplanner.tfl.gov.uk/user/XSLT_TRIP_REQUEST2?language=en