PLEASE HELP URGENTLY

My boss has been away recently and I have been on my own from 8.30-5.30 3 days a week. The other nurse has been on her own on the days off too. We do live in a low risk area and it is a small practice but I do wonder whether its legal or not etc. Especially when we had an emergency in for one patient and I had to nurse and leave reception unattended.
I don't mind, but I do wonder what would I do if anything were to happen.

I'm in this situation one day a week on a afternoon. I've been doing this over a year and haven't had any issues. We do have a panic button next to the desk and in surgery just in case and if i go to the toilet i lock the door for 5 mins. Also there is always the phone to call 999 if needed. Also the cash is locked away.

I need some help and advice please!
My Work has asked me to work on reception all on my own with no one else around on a friday with the door unlocked & open for patients to come in...
Since I am all on my own with no one to be around to help me if anything happens will this be ok?
surely this is not safe?
Please
I would love a reply as I am really worried.