Well I'd quite like to have a nose around the Alms houses in Croydon - they have always been a mystery to me since a child. Theyre right in the centre, on the high street. I never quite got the concept of Alms houses when I was little, feel quite sorry for the people that live there given the state of that bit of town on Friday and Saturday nights - no double glazing!
Other options for buildings to look at, just a stone throw from the NLA would be Electric House, The Nestle Headquarters...and the building next door which appears abandoned but I really like it

then just round the corner from there you have the Town Hall and round the corner again from that is Grants, a big old department store frontage. There is also
an odd building along the High Street which I can never quite work out which has normal shop frontage at ground level but some kind of dome thingy on the top - maybe just decoration but I'm not sure.
Ikea is doable by tram from the NLA, assuming they have fixed the tracks!