If you are talking about a new electric cooker, then all the clearances (width and height) will be stated in the installation manual. If you don't have it, download it from the manufacturers website.
Normally modern cookers can butt up against cupboard units (ovens can be built into cupboards!) - no clearance is required. Just make sure the cooker is high enough so the hot plates are not lower than the worktop surface. Also, use metal worktop edge strips to protect the laminate.
Last year 64% of the questions asked in our forum were answered within our DIY project pages at www.diydoctor.org.uk/projects.htm The project pages are now separated alphabetically and your answers are accompanied by diagrams and the ability to see, and buy, the tools and/or required to complete your project. Use our search box to look for your answer and save a great deal of time and money!