In terms of features, NeoOffice (donations accepted) is huge, truly a viable alternative to Microsoft office. It includes all the basic components: Writer, the Word processing component; Calc, for spreadsheets; Impress, the presentation module; draw, for the creation of graphics and diagrams; and Base, the database component. The spreadsheet component has some sophisticated features like Advanced DataPilot technology, Natural language formulas, an Intelligent Sum Button and a comprehensive range of advanced spreadsheet functions.
The regular payments you have so far found will form the core of your household budget. You can now turn those into a formal list, either on paper or on a spreadsheet, and put the amounts into the next column, with a heading notifying the month. Before moving on to the next phase, add a further 11 columns on the paper or spreadsheet, with the headings changed to appropriate months until you have a column for each calendar month for a year. I have prepared an example budget spreadsheet to help you.