From Delhi - Beijing overland- Olympics!!??

Hello All,

Im just in the planning stage of a trip.
Starting out from London - India. Not sure which city yet but probably Delhi. Plan on spending a few weeks around India and then on over to nepal and along the himalyan trek hopefully taking in a few hikes especially everst base camp.

From there we will hope to head on to tibet for a while and then on to that new train in tibet from Lhasa to beijing (with sto overs along the way in china) and we hope to arrive in Beijing for the Olympics next August and hang around there for a couple of weeks!

From Beijing we will probably fly direct to australia Darwin or Cairns) and work our way down along the coast. We will probably stay in Oz for a year (working some of it) and then on to Oz. then heading back to London, we will stop off in Thailand for a few weeks.

What do ye think of this plan? If we set off in April to go along this route would we have the journey just timed to arrive in Beijing in August for the olympics??We want a balance. Not too much or too little time in each destination. Who would be the best company to book theses flights with??One way might suit us better all one way??Any problems with visas doing it this way? Trip from delhi to Beijing is over land
The flights i need to book are: London -Delhi , Beijing - Cairns/Darwin , Sydney-New Zea , New Zea - Bangkok, Bangkok - London
What ye think?
Please help me out!thanks