You might want to go ahead and get that visa sorted now-use the in person service available, you'll know the same day if your ILR has been granted-read this for full details:

UK Border Agency | Premium service for applications in the UK

It's pretty straightforward, you make the appointment and then attend, they take your biometrics, check your documents when you meet with the official, and a decision is made while you and your spouse wait in the hall.

They mail you the biometric residency permit card, takes about two weeks. I don't think you can travel without the card, though, so you need to get the appointment made ASAP.