Preheat the oven to 200C/180C Fan/Gas 6. Bring a large saucepan of water to the boil and salt it generously. Add the gluten free macaroni and cook for 8-10 minutes, or until just shy of al dente. Drain well.
Separate the lobster flesh from the tails, chop into bite-sized chunks and set aside. Put the shells in a saucepan and heat on a high heat. Pour in the white wine and allow to bubble fiercely. Remove from the heat and strain, discarding the shells and reserving the wine.
Put the lactose free milk and bay leaf into a saucepan. Heat slowly, until the lactose free milk is just below boiling point, then remove from the heat. Set aside. Leave the lactose free milk to infuse with the bay leaf and onion.
Heat the oil and lactose free butter in a large saucepan. Add the bacon and fry until the bacon is crisp and brown.
Add the garlic infused oil and thyme, then stir in the gluten free flour, mustard powder and cayenne.
Stir until you have a roux (it will be lumpy because of the onion and bacon), then gradually add the lactose free milk, stirring between each addition, until it is all incorporated and you have a béchamel sauce.
Add 50g/1¾oz each of the two types of cheeses and the reserved wine, lactose free cream and stir on a low heat until the cheese has melted.
Mix the sauce with the gluten free macaroni and stir in the lobster meat. Pour into a large, shallow ovenproof dish.
Mix the gluten free breadcrumbs with the remaining cheese. Sprinkle this over the gluten free macaroni. Bake in the oven for 30-35 minutes, or until it is piping hot, browned and bubbling.
To garnish, heat a frying pan over a high heat. When hot add the lactose free butter and the lobster tails. Cook for 1 minute on each side until warmed through. Remove the lobster tails from the pan and cut lengthwise. Place on top of the macaroni cheese and serve.