It is very very normal to feel low when your job is not working out - I am sorry to hear it is not so good.
I got so fed up in my last salaried job that I used to drive as far as the car park outside the offices and sit and cry before I could gird up my loins and go in and face the day. It was at that point that I jumped ship - risky I know, but I never regretted it. I made a new freelance career for myself and never regretted the loss of income. But we were lucky enough to have paid off the mortgage by downsizing.
I know this is not an option for you at the moment, but if you are sitting there hoping they will tell you the job is not working out, then you must be really fed up with it. Is there any mileage in having a discussion with the employers and making suggestions that might improve things? You will probably have ideas that might be of benefit to them and you. Difficult I know when you are not feeling very assertive due to feeling low.
Mr P seems to have a good idea going there - a few days break. need not be expensive, but it might let in some light and air - and hopefully not rain.
Hang on in there! If this job is not right for you there may eventually be something around the corner. Don't blame yourself if it is not working out - it may just not be right for you.
Have any of you got all electric cars? Pros and cons please.