How do you guys manage ordering from different pharmacies?

Hello guys. I am not a rich man, and so naturally wish to keep my costs as low as possible. I just got my first dose today, and everywhere in the instructions it says things like, "If your needle is bent, throw it away and use a new one", and "If the pen doesn't reach the dose, it means there isn't enough, discard your pen".

But as I wouldn't notice these issues until I am about to inject myself, what am I supposed to do in that situation if I don't have a reserve supply? Also, if the pens last 4 weeks, when should I be ordering a new one? Naturally I have to contend with the pharmacy approving it, and then Royal Mail getting it to me, both of which could have delays. I suspect it's even worse if you are changing pharmacies every week trying to get the best deals.

So I was wondering how you guys go about it, especially if you're registering with a new pharmacy every month.

Any and all advice is appreciated. Thanks.