welcome to the fold m8
the scoob should have had 2 timing belts by now due to time and all the other service parts as per yearly or mileage whichever is 1st as with every car,
could still be a very good scoob but i would defo take someone that knows there way around an impreza with you and you should take into account you will need a FULL service including all oils, filters, belts and tensioners, anti-freeze and spark plugs, basically all service items
massive bargaining point i would be looking for £500 off the asking price at a minimum