The Idea
So much has been written about ideas before and applies across the board & there are not many UK specific aspects to factor in, here are some quick thoughts.
First thing you want to do is validate your idea in one way or another. In my view the best way is always to try and get payment early even if the product is not built (you can always refund people after) make a quick and simple page explaining the service and throw a buy button on it and get this in front of people
This may not apply to all ideas, not everything is something people can “buy” but think about what might be an alternative strong signal.
Don’t worry about people “stealing” your idea
Ideas are cheap (It’s all about execution)
Development is “easy” – Distribution is key
At the same time try to avoid letting external opinion sway you too much in a overly positive or negative way – Startups are a rollercoaster it is important to keep as balanced as you can.