London/Southampton Day Before Cruise Activities with Toddler?

We are flying into London on August 30, the day before our cruise, and trying to figure out the best plan to take advantage of our day. We are a group of 4 adults + 1 toddler 19 months). Does anyone have recommendations for good toddler activities in London, Southampton or in between?

We are flying into London on August 30, the day before our cruise, and trying to figure out the best plan to take advantage of our day. We are a group of 4 adults + 1 toddler 19 months). Does anyone have recommendations for good toddler activities in London, Southampton or in between?

This is a really good website for places in the UK to take kids (I'll show the specific London url): http://www.dayoutwiththekids.co.uk/things-to-do/London