Dissertation
LitCharts – literary analysis of hundreds of books.
Literature Map – type in an author you already like and the website comes up with others that are similar.
Association for Scottish Literary Studies – valuable if you are focused on Scottish authors.
BBC Sounds is worth checking for programmes about your chosen author and/or works. In particular look at In Our Time which discusses a specific topic each episode with academic researchers, and the Books and Authors thread, but there are plenty others.
You’ll need to create your own log-in for the BBC.
The British Library website is full of literary treasures. Click in the ‘Search our website’ box, type in your chosen author, title or theme – you never know what might pop up.