Quietest way would be to carry straight on from Kelvedon Hatch through Stapleford Abbotts and Chigwell Row. I always found this the best route into London from Essex. From there I jpined the A113 and headed towards Stratford, this has a couple of unpleasant bits (roundabout at the North Circular being the worst) and someone for familiar with London may be able to suggest a better alternative here. Even so, it's a lot better than going through Romford.