If it’s all done in Photoshop already, just save each file as a PDF, combine in Acrobat and print from there.
I did all the initial designs on Photoshop, however, the save the date cards require me to print on both sides. I was told that in order to do this successfully, I need to put the work in to indesign.
Let's start by saying this is probably nonsense, but how you intend to print will make a difference. If you are doing the printing yourself, and you have a printer capable of two-sided printing (pretty unlikley on card stock) then ID can make a two page file that will duplex. If the printing machine can't print two-sided on the chosen paper, it really doesn't matter.
Now, on to more important matters. How did you move your work from Photshop to ID? And how was it saved in Photoshop? ID can import quite a few image formats from Photoshop, but if you have type or other vector content that you want to keep crisp, you need to save the file as a Photoshop PDF for placing in ID. Any other format will result in the Vector content being rasterized and going jaggy. Also, you must Place the art, NOT copy and paste from Photoshop (File > Place...) or all you will get is the screen preview.
If you've placed the art, and it still looks bad on screen, either you've scaled it up or it doesn't have sufficient resoltuion to begin with, or, very likely, you just haven't got your display settings correct. By default ID uses "Typical" display, which gives you a low resolution proxy for the placed art. For a better preview (but still a preview) go to View > Display Performance and choose High Quality Display.
The broader question here is why all the work was done in Photoshop, and I presume that's because you are more familiar and comfortable working with that application. InDesign has a lot of advantages, though, for this sor of project, not the least of which is the ability to make a mulipage file. In ID you can place many pieces of external art and set the type, and maintain the quality of all the pieces. These days I rarely even build a photocollage in Photoshop, as I find it's much easier to control sizes and postions of the images (previously edited and masked individually in Photoshop, as required) in ID.
How about providing some details about how this is all going to be printed? With more info, we can offer better advice.
Thanks to both of you for replying!!
Firstly, let me start by saying that I actually feel really stupid as soon after posting I managed to figure out both of the "issues"!!
Peter, I had placed the image from photoshop, but as you yourself answered, I had not changed the display settings! Once I changed to "High Quality" it did infact clear everything up. As for the printing, I had it selected as "face fronting" rather than keeping the box unticked. I did a test run at home it worked fine. I will however be taking it elsewhere to be printed properly so I just need to ensure that they can handle double sided printing.
As for why the work was done in Photoshop rarther than indesign - I had done some work in both illustrator and photoshop to start off with and just kind of fell in to completing it all in photoshop. However, I'm not a huge fan of indesign if I'm completely honest!
Bob, thanks for your advice too - that actually seems liked a much simpler option!!!
Thanks again to both of you