What civilization claimed briton and, in doing so, introduced cities, roads, written scholarship, and christianity?

The correct answer is - The Roman civilization.

The Romans invaded Britain, even though it took them some time, gradually they managed to get under their control most of what is now England and Wales. With their arrival, the Romans brought lots of things from their society, including alphabet, thus reading and writing, they started to create cities with solid defense systems, and gradually were building roads in order to connect the cities they've built in order to enable better and quicker communication between them. Also, they introduced the Christianity in Britain. It is debatable about the exact time, there are some sources that claim that it was introduced as early as the 1st century AD, but officially it is considered that there was enough mass of people and preachers in period of the 3rd and 4th centuries so that it can be considered as a living, practiced, and prospering religion.