If I'm completely honest, I don't think this letter is very professional. Firstly, switch the "Good morning" to "Dear sir/Madam/Mr...."
I would also put something in there about having the right skills and experience required for this role, rather than just saying you are polite and confident.
I would also leave out the "hard worker" bit and also the "I am available to start work immediately and can work any hours".
Maybe change that for something like " I am available for interview at your convenience and, due to having no other work commitments, I am very flexible with regards to working hours"... or something like that.
End the letter with something along the lines of "I look forward to hearing from you shortly. Yours sincerely...."
"Many thanks" sounds a bit casual.
Also, maybe follow up every email with a call, a couple of days later.
Hope this helps :)