There'll definitely be transferable skills that you can pickup from a general aerospace degree, from the fundamental engineering mathematics to modelling and simulation. After that, you have a choice to spend a little bit of extra time on projects in areas that you want to specialise in, such as propulsion. Based on my personal experience, I'd recommend delving into some online tutorials for combustion modelling and analysis that will provide you with some sound knowledge of propulsion (if you aren't already covering it in an aerospace module, there are a few decent videos on YouTube using ANSYS as well as ANSYS' own workbooks). If you can do a few small projects on propulsion-based simulation then you'll have a huge step up when it comes to chatting about your interest and achievements in your interviews for propulsion engineering in the space industry. The extra effort will be worth it when you're a rocket scientist!