In the most part yes. Certain conditions are likely to be needed such as local planning and build regulations but you may need to consider your location, amount of available space and the local environment and ecology concerns of your dwelling.
No two extensions are the same and as such estimates are made on an individual project basis. You should consider what works you want to achieve and consider that specification of kitchens, bathrooms, wall tiles, flooring and electrical fittings among others as they can all influence the overall costs,
As part of the quality assurance we can offer you will also benefit from building control who make periodic inspections at key stages to ensure compliance, As part of the design planning the principal designer will provide drawings and structural calculations and upon completion MJ4 will issue you with technical certificates for electrical systems, Gas safe certificates and appliance user guides.