I self taught edexcel c1 and m1 this year. C1 will definitely take you more than a week, especially if you want to be getting A grades. It took me about a month to finish c1 (i was doing 3 other a levels at the time), and around 5/6 weeks to do m1. M1 was slightly trickier, cause you wont be familiar with most of the topics as they aren't taught at gcse, but it was my favorite unit. I watched almost all of the hegarty maths c1 videos, and for m1 I watched all of the exam solutions videos (which were an absolute lifesaver). I'd recommend doing as much of the questions in the official edexcel maths book, including the review exercises which are VERY USEFUL, and once you've finished learning everything, do as many past papers as you can. Good luck!