I don't know the finer detail of your company structure, which person has left, which poor mug has now joined, who does this and who does that. Neither do I care. I want the invoices you owe paid and I don't give a f**k which one of you lot does it, as long is it gets done, now!!! You're the boss, you sort it out!
Ideally, you'd put it off until you're better prepared but I don't think I did more than eight miles before my first half. It wasn't much fun towards the end but I got round OK and I'd imagine you will too. Definitely don't try and cram in any long runs between now and then though!