I have been prescribed diazepam whilst doctor sorts out my antidepressant.

Please don't worry. You are on a low dose. I have been taking Valium for 25 years with no problems. I may take it, for example, for 10 to 15 days. Then I will not take any Valium for 2 to 3 days. Then if necessary I may take it for maybe 10 days, then stop for 2 to 3 days. I take it for muscle problems. I had to quit one time for a few months then I went back on it. I did not have any problems at all going off of Valium and when I started taking it again there were no problems for me either. I take two to three 5 mg tabs per day when I do need to take it. I never take it any longer than 2 weeks before I take a 2 or 3 day break from taking Valium before resuming it again. My doctor told me he understood that if a person were to take Valium everyday for 3 to 4 months then that is when a person can develop an addiction problem. Just remember to take a 2 or 3 day break with no Valium before you resume taking it, if you need to. The key to taking Valium long-term (as my doc explained to me) is while you are taking it just remember to take a couple of days off from taking Valium every so often and you will be fine.

Hi, mum!
You're taking a low dose and only taking it as needed so it's unlikely that you'd become addicted. Addiction tends to happen most frequently when you're taking it daily (and often several times daily) for longer periods of time. That's why it's prescribed at the lowest effective dosage on a short term basis.
If you need it then you shouldn't be afraid of taking it. It's there for you to help you through the worst of the stress and anxiety.
Chances are once the sertraline becomes fully effective you won't need the diazepam any more.