do mortgage companies check credit card statements ?

It will certainly be one of the things looked at, yes. More important is your ability to repay amounts borrowed.

Why would anyone use a credit card to gamble with, it's bonkers.

No, they wont look at what you've used your credit card for, they most likely want your last 3 months bank statements. Important thing is that you havent had any missed payments on your credit cards. Make sure you're registered on the electoral roll as well.

i use my mates credit card to bet with and he just successfully remortgaged his house

It depends totally on who the Lender is and how strict or otherwise their Credit (Lending) Policy is.

Most will want Bank Statements to assess your income and expenditure and providing you pay credit card bills on time and have no arrears on credit card payments they will not want to physically check the itemised bill.

In some ways its better to have a few cards as it proves that you can be trusted to repay money that you have borrowed - I know of people who have failed credit scores due to having no credit - the logic being that you haven't proven you can repay it if you have it.

The key decision points will be-

Loan to Value - what % of the House value are you borrowing.

Have you got verifiable Income and a verifiable work history.

Do the income multiples stack up e.g @ 3 to 3.5 x single salary or 2.5 x joint salary.

Is the great majority of your salary fixed i.e make sure you aren't reliant on bonuses or sales.

What's your Disposable Income....the difference between what you currently earn and currently spend - will it support the mortgage payment (this will include an endowment or pension linked if you are paying interest only)and will it support essentials like House Insurance and utility bills etc..

Hope this helps..

I use my card a lot for both betfair and other accounts and i got approved last July, they look more at your savings record and propensity to pay back. What you could do if they question you is say that you use your credit card for a mate who is funding his account through you and you are putting a stop to it. Then you could use paypal instead to fund your account.