Pulling together a fun-filled extravaganza for a troupe of toddlers with sky-high expectations can feel like a tall order.Let the team at Stage Star Party take care of the entertainment. The West End professionals bring everything you need to your home, from sets and makeup, to stage a minishow starring your kids. Plus, they even supply the goodie bags.For the food, call the girls at Delicious. Cupcakes decorated with rocking horses or teddy bears accompany all the supplies you need for a tea party. Or try Cakes to Your Door for home-baked, colourful cakes delivered right to your pad.Sometimes it pays to take a few shortcuts.SEEOpen HouseWhat: An annual peek into some of the capital’s most intriguing buildings, with a photography competition for the under 12s.Why: It’ll blow the house down.When: Sat. & Sun., times vary.Where: Venues across London. For locations and bookings, go to londonopenhouse.org.READCounting Birds What: A beautifully illustrated book by Alice Melvin for number novices.Why: It’s a page-turner.When: Just before bedtime.Where: Tate Modern, Bankside, SE1 9TG (020 7887 8888).WATCHPeter and the WolfWhat: Mime, music and puppets with the Sea Legs Puppet Theatre.Why: The world’s a stage.When: Sat., 11:30 a.m. & 2 p.m.Where: Tricycle, 269 Kilburn High Rd., NW6 7JR (020 7328 1000).