Photographers tend to fret over the slightest marks on lenses but in practise you might be surprised how big something needs to be before it can be detected in images. I'd be surprised if those marks on your lens cause a problem.
However, as others have said, hard to tell from here, but that does look a bit like fungus. If it is and the lens is returnable, I'd return it. The problem is, unless you can kill it, there's a chance it can spread if, say, you keep it in a bag with other lenses in a damp environment (like all of the UK). If you leave it on a windowsill in dry air and bright daylight for a week or two, that can work, but it's hard to know for sure and do you want the aggro?
This is one reason why buying used lenses on ebay from far-eastern dealers that look like a great deal sometimes turns out not to be.