yeah all of the above options + Westminster Abbey, Houses of Parliament, go to Camden and laugh at freaks trying to be alternative and all dressed the same in designer gear, go for a drink at St Catherines Dock / Tower Bridge area, go for a pub crawl along the Thames from Hammersmith or Richmond etc oh and do all the cheap 'rugs you can at the same as all of the above.
On your last day go to a walkabout, read the NZ News, get wasted on kiwi beer and moan that nothing is as good as back home