Sometimes when the car is started it makes a loud screeching/grinding noise which is really loud, was wondering if this sounds like the starter motor failing? My father seems to think so and is a mechanic. We had it planned to change it past two weeks but we not got time at the moment and I need it changed urgently.. How much would it cost to get it replaced if I can provide the parts myself? Or does it not sound like the starter?

You can pick up a brand new starter motor for £45 if you look around (got mine from ebay). As long as you have a set of axle stands a good scoket set and a trolley jack, it can be done by yourself.