Hi Little UK,
From my experience, the Bridging Visa doesn't have an expiry date. You will be on the Bridging Visa until your visa 820 is granted. It could take up to 20-25 months, but stay positive, I got mine in 7 months (I was married the time I applied)
The grant usually appears out of the blue, considering that you've given your CO all the documents they requested for. I guess it depends from CO to CO, maybe some are busier than others. It seems to be just a waiting game, really... Goodluck!
From my experience, the Bridging Visa doesn't have an expiry date. You will be on the Bridging Visa until your visa 820 is granted. It could take up to 20-25 months, but stay positive, I got mine in 7 months (I was married the time I applied)