I have heard of bootstrap, but all the sort of idiot proof GUI frontends for it cost money.
What sort of frontends have you been looking at?
Ideally later features would include a fillable form where a client can tell me some basic info about their case.
Provided that all you want is that information to be emailed to you, and assuming that the form is already built, that's only a couple lines of PHP code that can be looked up online. I probably even have an example page I could share with you, if you go down this route.
Possible even later features would include some sort of more in depth survey link
I would suggest something like survey monkey for this, just to throw the only such service which name I can remember right now.. Building your own solution would just be cumbersome I think..
possible even later (fantasy?) feature would be some sort of client login where they can upload and download docs for their case.
The entire site you have described with all the bells and whistles would cost a couple grand, if you hired someone to do everything, from the design of the site to the implementation of all the functionality. It depends on the details, so I can't really give a more precise estimate.
But since you're building the site yourself I think and just want a form that emails you.. easy, that can be all done for free. You can do that stuff easily I think. Then once your business grows you could invest some money in building a login area with whatever features you have spent the last couple months thinking up while you gauge the ups and downs of various aspects of your business.
During that time you could also learn PHP and build a simple login area yourself. All you need is a login form, login authorization code, a bit of code that gets included on every page which checks if you're logged in or not, and a page that logs you out and clears the session. It doesn't take much code at all to accomplish all of that and there are many code examples you could look up online.
The way I approach any development project is .. baby steps. Say you have a login area built, you might then be comfortable enough to try to write code that uploads stuff and saves it to the server. PHP is sort of annoying to work with when it comes to files and anything time or date related.... but uploading of a file is actually only a couple lines of code too, and there are many example snippets of code out there too.
My last piece of advice for now is this: Don't ever try to have a scenario in which you are sending a file attachment via email and you need to write code to do this using PHP... while you're still getting your feet wet with it..
