Have you taken a look at the IKEA web-site / catalogue? They usually show different kitchen configurations and have ideas for getting good use out of small spaces. They also have a kitchen planner tool, that allows you to draw a simple plan of your kitchen and try out different options of units and colours and gives you a 3-D model that you can look at from different angles.
Alternatively, if you're not sure about planning it yourself, take some measurements and try one of the various kitchen suppliers like B&Q etc. - most of these offer a free design service where they will try out the different options for you.
Generally, in kitchen design you want to create a 'working triangle' between the sink, the cooker and the fridge, as these are the areas used most. In a small kitchen, think about maximising work surfaces and storage - if you have a window, keep the cooker as far away from it as possible. Also, if it's specifically for use by an elderly person, think about heights of wall units / shelves (how accessible will these be?), non-slip floor surfaces, choose easy grip handles and taps and easy clean surfaces when choosing worktop and cupboard styles.