Heat the olive oil in a paella dish or heavy-based saucepan and quickly fry the prawns until cooked. This should take only a minute or two. Remove the prawns from the pan and put aside. Add the chicken thigh pieces to the same pan and brown all over for a few minutes. Remove the chicken pieces from the pan and also put aside. Next, add the chorizo and pancetta to the pan and fry until crisp and golden brown. Add in the chopped garlic, onion and pepper and cook for 3 minutes to soften. Next, add the thyme, chilli flakes, paprika and rice to the pan and stir until all the grains of rice are glossy and coated in oil. Pour in the dry white wine, followed by the saffron strands and continue to cook till bubbling. Make the fish stock by dissolving the fish infusion stock pot in 350ml of boiling hot water. Pour the hot stock into the pan, along with the browned chicken thighs. Season well with salt and pepper, then turn down the heat and cook for a further 15-20 minutes. Next, add in the mussels, peas and chopped tomatoes and continue to cook gently for another 10 minutes. When the rice is cooked, scatter over the chopped parsley, arrange the cooked prawns on top and serve immediately.