Whilst I'm sure that plans have been made for public transport in the Olympic period in London, I don't think you have given us enough information as to what routings you plan to take.
if the local travel is good in and around the major cities in Europe?
is far too vague to answer as you don't name the countries or cities concerned.
For routings and train journeys I suggest you look at www.deutschebahn.de
which is accurate and covers Europe as well as Germany. Normally tickets in Europe are sold 12 weeks before travel.