[Your Street]
[Your Town]
[Your Post code]
[Date of letter]
[Human Resources Department]
[Company Name]
[Company Street]
[Company Town]
[Company Post code]

Dear Sirs,
Please accept this letter as notice of my resignation from the position of [Your Position]. My last working day will be [Date of last working day - usually 2 weeks notice]. As per my contract I am giving you [Contractual Notice Period] notice of my intention to leave.
[Optional Paragraph: I would also like to say that it has been a pleasure working for you and I wish you and the company nothing but success.]
Yours faithfully,

[Your full name]