I would usually say to contact the DVLA about this as we don't know for certain, however, you'll have a tough time getting through to them currently. I'd venture a guess that you are covered by the new one seeing as the licence itself has been processed. In fact, under Section 88 - you don't need to be in possession of the licence as long as it's being processed by the DVLA when the old one expires. Therefore, as long as you have proof it's been approved, then I'd assume you're considered as a valid licence holder. Do you know when/if you'll get it back in your physical possession? Unfortunately, we can't be sure as we've heard mixed messaged from other readers about similar situations.