iOS App testing - Low Budget Solution

So I am currently building my first iOS iPhone App which I plan to launch in the coming months. I have now finished my app but I don't have a big budget so testing on multiple devices is difficult. I already have an iPad so I assume that could run an iPhone version just to check that all the code is working. If I know that the code can run on an actual iOS device (the iPad) will the simulator suffice for the rest of testing would you think? I do plan to use test flight later on in the project too.