Can anyone help me with patenting an invention?

[ATouchOfStuffing]

I have had my idea for years and now finally want to use it.
I am unsure of how to start; do I need a prototype first? If so who would be best to approach for this (engineer?) and how do I protect the idea from them?
It seems to be a catch 22.
If anyone has any idea of costs involved that would be useful too. I am aware patenting should cover China as cheap copies can be made and re-sold overseas, but there is no such thing as a worldwide patent.

have a look at the Intellectual Property Office website here

my belief is that you need a patent attorney to advise you - usually a free initial consultation, and confidentiality is part of the deal. they usually get their clients via google or yellow pages so don't feel at a disadvantage doing this. i'd advise going for one near to you to cut travel costs, and perhaps look for a small/one-person firm as costs may be less. disclaimer - my partner is a patent attorney but not practising atm so I'm not advertising.

Ah thank you! So I go along to them before doing a prototype and they can draw up something for the person doing the prototype, I guess?
Will look at the link now, thanks again!