You should ring a few local electricians for quotes. They will want to know the following: Is the cable for the electrical connection in place and long enough to reach the oven. Is the gas hose in place and long enough to reach the oven. If both of these ar OK then I would think €50 to €100.
Think you might need a plumber to connect the gas hob. My experience with these tradesmen is that they will not attempt anything for which they are not trained. They could not stand over the work. However any good DIY man should be able to connect the electric cooker providing the cable is in place and it just needs to be connected. The gas connection would be a different story.