There are very few moving parts (which can create unwelcome noises) inside any computer. One of these is the fan which cools the processor. So, a combination of noise and a burning smell suggests a faulty fan.
If it's just the fan which needs fixing, it shouldn't be very expensive. (The fan only costs a few pounds. The main part of the cost will be labour but, even with a laptop, it should be a fairly simple job).
My concern, however, is about that 'burning smell'. If the absence of proper cooling means that the processor has been 'fried', replacing it could be expensive. It largely depends upon what type of processor the laptop uses. If it's a fairly basic laptop, the processor might cost around �50 (plus fitting). A top of the range laptop could use a processor costing well into three figures.
Chris