This long list constitutes a small selection of interesting (online) resources for finding primary sources. It can give you an idea of the range of options out there and which kinds of institutions make sources available and develop collections.
Reach out to Simon Elichko (selichk1) to get suggestions tailored to your topic.
Offers full-text access to English-language titles and editions published between 1701 and 1800 including books, pamphlets, almanacs, Bibles and treatises. Subjects covered include history, geography, fine arts, medicine, science, literature, language, religion, philosophy and law. Significant collections of women writers, collections on the French Revolution, and numerous eighteenth-century editions of the works of Shakespeare are also included.