What does a structural design engineer do?Watch
You will be scheming options based on the architect's layouts and making sure the building is designed to code while being as cost-effective as possible.
Depending on the contract you'll co-ordinate and manage other consultants such as geotechnical engineers and MEP.
The way to become one is to get an accredited degree in structural/civil engineering and join a company, the career is fantastic if you like building things and solving problems. It is relatively well paid in London, however don't expect a magic circle law firm salary.