Cheap / free day out this Wednesday in London

[emsiewill]

DDs and I are going to London to visit my db, dsil and dniece on Tuesday, staying until Thursday evening. As SIL is now 38 weeks pregnant, I have offered to take the 3 girls (aged 5, 5 and 7) out for the day on Wednesday. Trouble is, I don't have much (ie hardly any) spare cash, so am looking for something suitable for us to do that won't cost much. We did Tate Modern last year, so would like something different. They live near to Loughborough Junction, so something in that vicinity would be ideal.

Oh wise mnetters, can you help?

Science museum is free and full of things to fiddle with! Then you could walk from there to the Princess di playground and have a picnic. Or there's lots of city farms around that are free.

where is Loughborough Junction?

Loughborough Junction is SE London - not far from Herne Hill and Brixton, if that helps.

From Brixton area, it would be easy to go to:

*Battersea Park for a picnic, playground and a visit to the kiddie zoo (can't recall the admission price).
*Take the Victoria line (from Brixton) into Victoria. Walk to see the changing of the guard at Buckingham Palace, then go to St. James Park for a picnic, a visit to the playground, and to feed the ducks. Maybe have an ice cream. You could then walk down the mall to Trafalgar Square and see the huge lion statues, and the fountains.
*If it's hot and sunny, go for a swim at the Lido in Hyde Park. Walk past the Princess Diana fountain (closed at the moment), and just beyond the cafe. You'll see the sign for the Lido. It's £1.50 each to get in and it's a lovely kiddies only wading pool with play area (sand pit, swings, slide). Great place to take a picnic. I've taken dd a few times, and she loves it.