Another great book at that level is Student friendly Quantum Field Theory by Klauber. Especially if you struggle with the incomplete math treatments in standard books like Peskin & Schroeder, where the first chapter basically assumes you already know all the weird complex contour integrals that you usually only encounter in QFT. If Klauber says "from this easily follows ..." then you can expect to understand it even if you're not yet an expert. Ofc that comes with less depth in total, but there's no point in talking about renormalization if you haven't understood field quantization.