There is a smorgasbord of art to see as the capital heralds in the long-awaited spring. Culture-vultures can survey Francis Bacon’s perturbing animal-human hybrids at the Royal Academy, trace the evolution of Van Gogh’s portraiture through an intimate exhibition at the Courtauld, have behind-the-scenes access to the world of the artist’s studio at the Whitechapel Gallery, or even dive into the mythical world and history of Stonehenge at the British Museum.