What should I put in my resignation letter?

[peskyfeelings]

I've decided to resign from my job and I'm planning to hand in my notice letter to manager and HR tomorrow. I could really use some advice on how much content it should contain please.

I was off on long term sick from December 2015 up until July this year. The illness was due to depression and anxiety caused by my working environment. My company found me a new site to work at, and I have just finished a four week phased return to work.

It just isn't working out however. I feel just as stressed, anxious and overwhelmed as I did before going off sick. It's time to admit that the role just isn't one I'm capable of anymore. Do I mention any of this in my resignation letter, or might they then put those details into any reference they give to a potential future employer? I really don't want to compromise myself. Also, the company states four weeks notice, but I have more than enough untaken AL to cover this. Can I ask to take this as part of my notice period? The thought of staying there for another four weeks is horrendous.

Thank you for your help everyone. :)

You must feel so relieved that you've made the decision to hand in your notice.

Personally, I would keep it brief. If the company do exit interviews you could always give a bit more detail then.
I would just thank them for their help and consideration.

I always use google when I need to do this sort of letter. There'll be lots if examples.

Hope it goes well tomorrow.

I would keep the resignation letter short and not mention your reasons - as feather says, you can outline those in an exit interview.

Whether they will allow you to leave immediately depends on your current workload. They may offer to pay you for your holiday days instead. Who would pick up your work if you did leave immediately?

I can understand why you've made this decision but I would urge you to work with your counsellor to look at coping strategies and finding yourself a route back into work.

You don't hAve to write much in your resignation letter, pretty much, dear HR, please accept this letter as formal notification of my resignation. My notice period is four weeks, so my last working day will be X date. Wishing you all the best, etc.
You can discuss your actual leave date and accrued holiday with you manager or HR and agree physical leaving date and official leaving date when you hand your letter to them.
Hope that helps

Thank you for the replies everybody. It sounds like brief and to the point is the way forward, so I will do that. I've found a couple of likely sounding templates on the internet, so I will copy one of those.

Annoyingly my line manager has just gone on holiday for a fortnight, and there's no way I am waiting another two weeks to get this ball rolling. I will contact HR tomorrow and see what they say.

tribpot I have no idea who would pick it up. I've just come to the end of my phased return anyway, so I am really only due to get back into the thick of it from tomorrow. I really don't think there are any coping strategies a counsellor could give me to combat the level of misery working for that company gives me. I honestly don't think there are any more reasonable adjustments they could make either. I'm just not up to the job anymore. I'm actually planning to make a claim for ESA once I've left, and take some time to get my mental health back together properly. I should never have gone back to the job.