Learn about Regents Park trees on Saturday - image by Big Rock Cat via the Londonist Flickrpool
Friday: Tour the National Gallery collection after hours. Meet at Sainsbury Wing information desk ready for 7pm. The Gallery is open till 9pm every Friday.
Saturday: Take a free tree walk round Regents Park with a proper qualified arborist. Meet at Chalk Farm Tube at 11am (till 1pm).
It's free Photo Album Family Day at Whitechapel Gallery inspired by images from India, Pakistan & Bangladesh currently on show. Dress up for a family portrait, learn about photography and let the kids loose on gallery tours between 12-4pm.
Sunday: Green Sunday at Dalston's Arcola allows you to make your own wind turbine, or an LED out of recycled mobile phone chargers, play bike powered Wii games, join in discussions, film screenings and don't forget to partake of goodies from the organic cafe. Free, 12.30-7.30pm.
Free film noir this afternoon as Night and the City is screened in the Museum of London's plush new theatre between 2-4pm.
Monday: The folks behind the madness that is Showtime Challenge present WriteBites at RADA tonight. Brand new scripts get minimalist stage debuts with the chance to discuss them over a glass of wine after. Just £3 on the door, starts 7.30pm.
Tuesday: The Liar's League present 5 'sweet and sour' stories downstairs at The Phoenix, Cavendish Square W1 from 7.30pm. For just £5 expect tales of languid vampires, car-park adultery, dissolving marriages, disastrous reality TV, and a very special game of Deal or No Deal.
Wednesday: Without encouraging boozy lunch hours, get to the London Drinker Beer & Cider Festival in the Camden Centre between 12-3pm today and it's free (we recommend you buy some of the CAMRA catered, homemade lunch though).
In the Lilian Baylis Theatre at Sadlers Wells there's a bargain tonight. Tickets for the The FATHoM Project are just £5 for a double bill of powerful "total theatre".
Thanks to everyone who tweeted up tip offs - please keep them coming. Tweet @londonist #lotc to get your cheap and free events listed each Thursday.