Small attic conversion over a 2 bedroom terraced house already has 100mm insulation in sloped ceiling and 100mm to sides of attic rooms walls leading to 2 small storage areas where the cold water tank sits. Quoted 1500 with VAT to get insulated walkboards added to floor of storage space, add more 100mm insulation to sides, jackets for large and small water tanks, insulate 2 attic hatch doors and roof ventilation. Is this about standard?