My dilemma is that I have the ability to design and develop my web concept to a certain extent and I'm doing courses to equip myself with as much knowledge as I can get to take it as far as possible.
But at some stage I'm going to need to hand the concept over to a developer and pay them to apply the functionality I can't.
I have one friend that I trust who's fully qualified; but he declined as it could put pressure on our friendship. I could patent it but in the web world, there are just so many ways to make that null and void.
What is your primary concern? That one of your developers / friends will steal your idea? Or that once it is released to the world someone will make a copy of it?
If it's your development team then have them all sign confidentiality, non-disclosure agreements, non-competes and work for hire agreements. This should adequately protect you should one of your team want to steal your idea.
This is what the Winklevoss twins needed when they started working with Mark Zuckerberg and he went and created the idea on his own as depicted in the book/movie The Social Network. Even without those documents they got a pretty huge payout.
If you are worried about someone cloning your idea then you can invest the money in patents and get some lawyers working on it. However, this probably will make no difference. If it's great it will get cloned/copied just like every great web service. There are Stack Exchange clones, Groupon clones, eBay clones etc.
Ideas are a dime a dozen. Building and selling them are the differentiator.
Don't worry so much about it and just get to work :)
The simple answer is: you can not protect yourself from ideas getting stolen.
The best you can do is to use, as already suggested, NDA's for everyone involved. Even then you will not be able to protect yourself fully as there can be several methods to achieve the result your idea targets (especially in the software world).
My advice is to not pick the "first and best" developer(s). Do research on the potential team you want to hire, look at references, run-time, customer list (if possible). It doesn't have to be a huge company. Have a meeting with them before hiring to get to know them, see if you connect well and so forth. This will help you making a better decision in who to hire.
When it comes to patenting: you cannot patent or copyright ideas. This is a common misconception. You can only copyright a manifestation of an idea (ie. think chair, no one can copyright a chair itself, only the design for a chair). Patents cover methods and they need to be unique and non-common (which is very hard to achieve in software development - and there exists many questionable grants for patents in the software world - but that's another topic).
However, if you do feel you have a unique method I would recommend you patent it anyways. This way you'd at least have a legal card later if someone else uses your patented method without permission. If not, you could end up being the one using the method illegally if someone else comes to the same method and patents it.
Sorry, my first answer was a bit off. It incorrectly discussed protecting a website against browsing.
If you opt to patent the idea, great, just realize that most small companies cannot afford the legal battles necessary to win a cut-and-dry patent case.
One approach, that is quite problematic.
You can attempt to partition your website into independent chunks and have multiple developers each working on a chunk that by itself doesn't expose the core ideas, but in combination functions as you wish. A problem with this approach is that it places the integration of the parts on your shoulders, where software development experience is lacking, but an even bigger problem is that if you make poor choices in dividing your software, you will have a piece that needs to attach to other artificial divisions that don't support it. In short, to do a good job at this, you might have to be a software developer.