Maybe this is a basic question but I can't find anything that has convinced me either way. I am using ajax to send fields to be saved by a php page and it seems like it would be an easier solution to post them rather than mess around with url encoding
First of all, if you want to manipulate data in your model, you should always use POST and not GET. GET method philosophy is to be used in case of data retrieval.
Consider for example this: stackoverflow.com/questions/198462/, or even this: Wikipedia's thoughts on POST
And in answer to your question: Yes, you can. And if you have any problems with character encoding just make sure you're using the same encoding settings everywhere (webpage encoding, PHP mb_internal_encoding, MySQL encoding, etc.)
you can use encode url which takes care of special characters.
Refer this