Whatever else you do take pictures. Its reasonable to expect tenants to leave accomodation in the state they found it (minus unavoidable wear and tear) its perfectly acceptable to clean it yourself aslong as its to a good standard - if you have photographic evidence that you left it in a good state they don't really have a leg to stand on.
You need to go around the house with agent/landlord and sign it off then and their. Only if there is a dispute which you can't agree on would I take pictures.
Also don't leave the carpet cleaning. If they are in very good nick hire a washer yourself. Big supermarkets do them. If in poor condition get a professional yourself in. Ensuring to keep receipts.
Professional standard just means super clean, no reason you can't do it yourself. Just remember to do hidden places, like top of cabinets or under/behind anything moveable.
Give yourself a minimum of three days with an empty house. Preferably with agent/landlord coming at end of second day. If no arguments sign (get written with both your signatures, with an agreed time frame for deposit if not allready in contract) if any disputes keep keys and you have a day to fix it.
It really is worth doing it yourself and taking time, £600+ is a lot of money.