How much money you can physically raise all comes down to how many people you can reach. This will be a mixture of your crowd to get the ball rolling and the wider crowd if the idea is good enough to spread.
The average amount that a supporter will pledge towards your Crowdfunder project is £50. So for every £10,000 you aim to raise, you will be looking to find on average 200 backers for your project.
It's important to remember that not everyone will pledge on your project. This means that for every £10,000 raised, you will be looking at getting between 1,000 to 4,000 people viewing your project page.