We have a different model smeg cooker but the way to rise the top/hob is to remove the cooker knobs on the from of the cooker; they just pull off. There are two small screws under the lip that secures the front panel (the bit between oven doors and hob where the knobs were) - watch out for the clear plastic bits over the oven dials on the reverse of the panel; they drop off easy. When the front panel is removed you should be able to see the two srcews that keep the front of the hob down. Remove these and the hob should open, hinged at the back.
Vincent
March 2008