I would just like to second what pete says about the budget and showing in DETAIL what money is avaiable to look after and support your wife.

The Ceo is looking to see that you are.

1 In love and its a proper relationship.

2 That both of you are either free to marry or legally married already to one another.

3 That either your wife or yourself can ensure your Wife is not a burden to public finaces at least for the first two years.

This can be done by a mixture of showing that you have spare income to support your wife, and/or enough savings in the bank. It could be your wife has enough to support herself in savings. That or you can show your wife has a job lined up. It also helps to show your wife has skils which can help her gain a job in the UK.
Basically the CEO wants to know that between the two of you, your wife is not going to cost the taxpayer money for the first two years.

4. That you have suitable housing which you either own,are up to date on your payments on mortage or rent and also if renting have permission to allow your wife to stay with you. Also that the accomdation is suitable for you both to live in. Ie enough rooms over the correct size etc.

Thats how i saw it from what i read on various websites and from what the goverment rules state.

Regarding the letter from employer i sent in my annual letter from HR which states my salary for the year ( i.e any payrise and thanking me for my hard work in the previous year and also my p60 and as i had them my last 6 months of payslips just to be sure.