Seriously struggling new F1

Hi everyone. I've just started f1 around 6 weeks ago and am having a really hard time, seeking some advice please.

I am on a surgery block right now in a smallish DGH and hating every second. When I first started I felt mostly OK but recently I seriously feel like I can't cope. This is mostly due to having to do a lot of on calls and nights in which I seem to spend the whole 12 hours panicking, being asked to review patients for things I have no idea about (covering every surgical ward and a few medical wards whilst on call so really anything can come up).

SHOs are generally sort of nice but very busy and often unable to help me with anything, and some of the SHOs are very reluctant and annoyed to give any sort of advice about anything. This whole situation just leaves me extremely stressed out every on call shift as I just seriously have no idea what to do for a lot of the bleeps and can't get anyone to help.

There also seems to be some sort of culture particularly amongst more senior nurses of condescension and mockery of early junior doctors which makes matters worse.

I know it's only been a short period of time but right now I feel I can't carry on. I've hardly been eating and I can't enjoy any of my limited time off as I'm so stressed/depressed about this job. I feel completely useless and just a burden on everyone at my workplace.

I honestly feel slightly suicidal right now because I feel trapped in the job and don't know how to feel better about this situation. I know it takes time and experience to get better but I'm finding it hard to even get through each shift never mind the rest of foundation. I somehow feel worse after every day. I have been seriously pondering the idea of quitting and working in tescos or something because I don't know how to continue feeling like this.

Sorry for the length, but I would really appreciate some advice because I feel at my rock bottom right now.