If I understand you correctly, what you need is called a "non-disclosure agreement". People in the new product development business call them 'NDAs'. I can let you have something to look at but I'm sure if you search the Web you'll find something perfectly acceptable. Before you discuss your idea with anybody you have to get him to sign the NDA, in the presence of an independent witness who also signs it, to say that he saw it signed. If you have a NDA then the person with whom you have agreed it is legally bound by its terms. If he ignores that (steals the idea, or tells other people when he shouldn't, whatever) then it's up to you to do something about it. That probably means the courts. That will be expensive, and everybody knows that, including the guy who signed it.
There are, more or less, two other ways to protect what's called 'intellectual property'. They are copyright and patent. Both have drawbacks.
You don't need to do anything to obtain copyright. Not even draw a 'c' in a little circle. If you produce something original, such as a drawing or a design, copyright is automatically yours. Proving it, however, is something else entirely, and anyway copyright doesn't really do a lot for you unless you're prepared to spend a lot of money in the courts at which point I'd say the game's up already. Copyright is world wide.
If you have an idea that is patentable and you intend to patent it then you MUST have an NDA with anyone to whom you show or describe the invention because if you don't, you have 'published' the invention. Whether something is patentable or not is a book in itself, but (even if it's patentable in principle) you can't patent anything which has previously been published. Patents are unfortunately not world wide, you have to apply for patents country by country, and the rules are all different in the different countries, and so are the fees. It is just about possible to patent something yourself, but given your skills with words I'd advise against it. It is possible to lodge with the UK patent office something which gets you started on a patent application and helps you to protect the invention while you talk to potential partners such as manufacturers. This only lasts a year, however, and you have that time to decide whether or not to proceed with a patent application or to withdraw the application unpublished. Once you have a patent it lasts for 17 years in the UK. UK patents are considered amongst the best in the world. They have a "high presumption of validity". There are European patents, I have no experience of them. American patents, well, do not have a high presumption of validity.
My personal opinion is that the best thing you can do is get to market fast and make a quick killing. Forget all about copyright and patents unless you're absolutely sure that the entire world is going to want one, and also that you really don't mind a few hundred rich lawyers and agents getting a lot richer by skinning you.
Oh, PS: This is not legal advice.