Questions from a First time traveller

Hey Guys,

Just have a few questions that i would like to ask.

I am doing the European Inspiration in October.

I am arriving into London the day before my tour starts at 11am and would like to know if there things i could do to waste time between when I arrive till the pre tour meeting (is it around 6-7pm??)

Also I have 2 full free days to explore and wander around London after my tour has been completed and was wondering if a tube pass or the hop on hop off bus is better to use.

Generally what time does the tour arrive back at the Royal National? If it is really late would I just book a late check in for the night?

Thanks!