I need to borrow money for a home improvement and add it to my mortgage but I have only had my mortgage for 3 month so I have been led to beleive I wont be able to do this so soon could anyone tell me different.
It depends on whether you mean a secured or unsecured loan.
If it's an unsecured loan then it would depend on your income, expenditure and credit rating.
If it's a secured loan - secured against your property - then it would depend on the balance of equity of your property. If your mortgage is for, say, 75% of the value of your property, then you may be able to borrow an additional percentage of the value, say, 10-15%.
By the very fact that sladeyp is proposing to add it to the mortgage, it would be secured. So the first 2 paragraphs of the above answer do not make sense.
Whether the mortgage lender will let you borrow more money doesn't depend on the length of time since the mortgage started, but it depends totally on the lender's assessment of your ability to pay it back. You will have to ask them, not us.