The cost of having an electrical hob installed in your home will largely depend upon the model that you choose, whether that is a freestanding model or fitted into your worktops. In most cases, people go for the fitted model and this may need some preparation work from your kitchen fitter or electrician to make sure that it fits in the space currently occupied by your hob.
If this is an entirely new installation (for example you are replacing a freestanding cooker or hob) then you will definitely need some prep work done on your worktops. Whether you are having a solid plate or ceramic hob installed, your electrician will need to connect the hob to the electrical supply and test that it functions correctly. This is a fairly simple process and an electrician will be able to provide you with a reasonable quote for his labour for the job.
Your electrician will also be able to fit any switches or sockets needed, or move any that will be impacted by the new hob. They will also make any necessary adjustments to your fuse box. Be sure you only use Part-P-registered electricians to carry out electrical work in your home, as this is a legal requirement for most kinds of domestic electrical work.