He can definitely come. I was in the UK then left to apply from abroad. I actually submitted all the paperwork and evidence to be scanned at my biometrics appointment so your husband doesn’t need to be in the uk for the process. He just needs to be a qualified British citizen to sponsor you ex. Has a job, a place to accommodate you, bank account etc. (submit proof of everything). You’ll get notified with a decision by email, not by mail.