I'd avoid the Gov't sett, if ONLY to avoid any sectarian misunderstandings. (Personally, I think it's a darling tartan, kind of like the 2d Gen Camaros---if they'd been a Ferrari, say, instead of a GM product and thus on every streetcorner, they'd still be turning heads with their good looks.)

With only a month left, that might well rule out a freshly tailored kilt, but if you've got a Cunningham on hand (or on hip!) I'd say go with it. Nice looking tartan, and good ties both ways (to you and Prince William).