Suitable writings for self-study in general biology/chemistry
My personal favorite intro biology book is Campbell Biology. The new edition is a little pricy, but you can probably find one of the older editions for pretty cheap--my intro class used 9th edition, and I don't think much has changed other than some of the taxon names.

I'm not sure what branch of Bio you're interested in, but Campbell covers all of introductory cell biology, organismal/evolutionary and ecology. The "concept check" questions at the end of each chapter are fantastic open-ended responses, and I believe most (if not all) have answers in the back of the book

I'm not as solid in general chemistry, but some good ones I remember are Brown, Lemay, and Burston which got me through AP Chem, and Zumdhal which my university uses and I haven't heard any complaints. The Brown text is a pretty good intro though. It provides good information and I thought it was pretty enjoyable to read.