I am quite sure they don't need to do any licensing to depict a plane that looks like a Vulcan (as long as they don't refer to it as one)... I mean, we are talking about a plane that's going for 70 years of age. And undoubtedly any necessary variation could've been more subtle.
I don't think PG wouldn't be able to model an Aermacchi MB-339 or... Whatever thing the jump jet is based on, with a satisfying degree of accuracy. So maybe their choice to go with a more cartoonish look has to do with ESRB ratings, rather than licensing issues?