Introductory R course from the Danish Diabetes and Endocrine Academy — held once a year, materials freely available. Best starting point if you are completely new.
Practical reference written for epidemiologists and health researchers — covers data cleaning, analyses and visualisation with health science examples.
Free e-book by Danielle Navarro — covers statistical theory and R implementation side by side, from basic probability to regression and ANOVA. Written for a non-mathematical audience. Relevant if you want to understand the statistics you are running, not just copy the code.