I have written something on environmental engineering here so I guess it gives you some introduction to what environmental engineering is about. Of course, today the scope of environmental engineering has widened significantly, and the growing awareness on the need to conserve the environment has brought about a huge demand for environmental engineers.
If you want to be involved in environmental engineering with regards to water and wastewater, solid waste management, or environmental-related fields that are not part of industrial wastes, then doing environmental engineering through civil engineering is quite a good choice. If you are interested in dealing with treatment of industrial effluents, air pollution, etc. etc. then doing environmental engineering through chemical engineering is the choice. I am not sure of what a chemical engineer really does, but personally I feel that a civil engineer has a wider scope in environmental engineering. Nevertheless, I stand corrected.
Being an environmental engineer does not mean that you confine yourself to just environment on the land, but offshore facilities would need environmental engineers, too. Even though you do not want to go to offshore platforms, drilling rigs, etc. it's still too early to tell. You may never know that one day you want to go offshore. The money earned offshore is definitely definitely lucrative.
If you are interested in chemical engineering, then knowledge of chemistry is of utmost importance - physical, organic and inorganic chemistry included. Chemical engineering is especially needed in oil-and-gas companies, and they can be very helpful in reservoir engineering. If you are dealing with hydrocarbons, then you cannot run away from all the alkanes, alkenes, alkynes, etc. etc.
Of course, chemical engineering is not all about oil and gas. You'll need to find out more about it yourself. If you want an idea of what chemical engineering is about, and how the curriculum structure is like in my university, then you can check it out here. It can serve as a starting point for you before you decide to join any university.
UTP is currently committing itself to research on Green Technology, CO2 Management, Sustainable Development, Energy, Enhanced Oil Recovery, etc. etc.
As for mixing with people and company politics, we need to live in a realistic world. Being an engineer means working with people, especially other engineers, and never alone. The engineering world is so vast that it has broken into numerous engineering fields, e.g. civil engineering, chemical engineering, marine engineering, electrical and electronics engineering, petroleum engineering, mechanical engineering, etc. etc. etc. Working and mixing with other engineers become inevitable.
Company politics depend on the company you work in. Some have more company politics, others have less. It depends on the working environment and the people you work with. You may have to face it yourself in the future, and there is nothing much that you can do about it.
Even if you decide to open up a consultancy firm by yourself five or six years after you graduate, it is not possible to eliminate company politics altogether. And if you decide to open up a firm by yourself, there's more reason that you cannot avoid mixing with other people, such as contractors, government officers, etc. etc. because if you want business, then you need to interact with others.