Best if you read the sticky threads regarding the Oneworld Explorer and pricing. In business class the UK is among the more expensive origin points in the world; there are other European origin countries where a 4-continent business RTW would be much cheaper than the UK.

As to your question, is there a better routing, well the number of possibilities is very great indeed, but it really comes down to where you want to go. Your route is valid, for what it's worth.

As to tier point earning, http://www.britishairways.com/travel...s/public/en_gb should help you calculate the results of any itinerary.