The iPhone/iPad simulator that comes with Xcode includes Safari. If you run Safari in the simulator, you can view your website and it should appear the same as it would on a real device. This may work for general layout testing. But since it is a simulator, it is possible that not every single bit of functionality will be exactly the same as using a real iOS device.
If you are writing a website and you need to verify that it looks proper on a given device, then you need to test your website on that actual device. Testing with real hardware is part of the price of doing business.
And yes, you need a Mac to run Xcode.