Сложно ли будет читать русскую классику на английском, если уровень языка pre-intermediate?

На мой взгляд - легко. Не нужно слушать тех, которые говорят бесполезно. Полезно читать что интересно, а не что надо. Желательно слова угадывать по контексту, прежде чем заглядывать в словарь. Вот пример из Толстого (я его всего прочитал, и я бы никогда его не прочитал, если бы не английский - совместил приятное с полезным):

Alyosha was a younger brother. He was nicknamed “the Pot,” because once, when his mother sent him with a pot of milk for the deacon’s wife, he stumbled and broke it. His mother thrashed him soundly, and the children in the village began to tease him, calling him “the Pot.” Alyosha the Pot: and this is how he got his nickname.
Alyosha was a skinny little fellow, lop-eared—his ears stuck out like wings—and with a large nose. The children always teased him about this, too, saying “Alyosha has a nose like a gourd on a pole!”
There was a school in the village where Alyosha lived, but reading and writing and such did not come easy for him, and besides there was no time to learn. His older brother lived with a merchant in town, and Alyosha had begun helping his father when still a child. When he was only six years old, he was already watching over his family’s cow and sheep with his younger sister in the common pasture. And long before he was grown, he had started taking care of their horses day and night. From his twelfth year he plowed and carted. He hardly had the strength for all these chores, but he did have a certain manner—he was always cheerful. When the children laughed at him, he fell silent or laughed himself. If his father cursed him, he stood quietly and listened. And when they finished and ignored him again, he smiled and went back to whatever task was before him.