What do I write in my notice ?

[FippertyGibbett]

I’m giving my notice in. I’m not happy with recent changes and I’ve decided I’d rather just leave.
I want to leave on good terms so that I can do ad-hoc work with the company when they need it.
How do I word a notice letter, and do I put in it that I’m available for ad-hoc work ?
What do I say about why I am leaving ? I don’t want to say why I’m actually going.

Thanks.

Here's my notice and the dates.
I have enjoyed working with you and especially blah blah
Wish the dept well in future etc

No need to give a reason.

[Insert your name]

[Insert your Address]

[Insert date]

[Insert Recipient name]

[Insert Title]

[Insert Organisation]

[Insert Address]

Dear [Insert manager’s name],

Please accept this letter as notice of my resignation from the position of [Insert job title] at [Insert company].

As per the terms of my employment contract, i will continue to work for the company for the next [Insert notice period length], completing my employment on [Insert last day you intend to work].

I have enjoyed being a part of the team and am thankful for the opportunities you have given me during my time here. If there are any areas in particular you would like me to focus on during my notice period, please let me know.

Yours sincerely

[Insert your name]