Can CiviCRM manage sales opportunities?
I don't have enough rep to comment and this isn't exactly the answer you were looking for, but I also had the same question a few months ago and research led me to the answer No. Instead, we are using Salesforce to manage sales leads (in our case, prospective members). I talked with a few people who have a lot of experience integrating CiviCRM for nonprofit orgs, and based on the small size of our staff they did not believe it would be worthwhile to customize CiviCRM to the extent needed, when an out-of-the-box solution would work just as well. I'm in the U.S. so I don't know much about Salesforce in the UK, but here there is a free version for nonprofits.