Hi !,
from my point of view, one of the most pleasant and simple books you may use to practise english is “English Vocabulary in Use” (cambridge university press). there are different levels of this course but information in all of them is structured and thematically organised which eradicates the fear and helps move step by step to more difficult level. besides there are not only words to learn but full expressions with exercises bellow. 

as for grammar i would recommend “Destination b1”. it’s also pleasant to work with this book, all the aspects of grammar are there and they are given in a convenient way.

and last but not least – fiction. the last book i remember i’ve read without any difficulty is “Bonesetter’s daughter” by Amy Tan, sentences are simple and short, vocabulary is descerned from the context and what’s the most important – very interesting plot.