When presenting your business plan to an angel investor you must understand that they will be very interested in your spreadsheets and proformas, but you must also realize that it is typically an entrepreneurial optimistic approach, which causes problems with proformas. Therefore, you should have dueling spreadsheets; that is to say the spreadsheets, which take your best guess and double the time, double the expenses to compete with your optimistic approach. You should be able to present both of these to your Angel Investor; who chances are is a retired business person with a little bit of financial savvy.
Going over what you have spent over the last quarter will cover most if not all of your regular payments. However, it is important to think about whether you have any quarterly, annual, or new commitments that may not have shown up in your previous search. This part of the process in making your budget should give you a list that includes utilities (eg water, electricity, gas and telephone), insurance payments, mortgage and loan repayments, and credit card payments.