I agree about letting the EAs do the selling. I don't like looking around houses with the owners there (not that I've bought many), and people are more honest with EEs, so you will get better feedback.
If there is clutter that can't be put away quickly and easily, maybe stash it in the car during the viewings? It's surprising how much more spacious houses can look with everything put away.
Put the lid on the loo(s) down, and make sure towels and bath mats are clean and tidy. If there are any small chips in paintwork, get one of those little touch-up things (a bit like a bottle of Tippex) and touch them up. Let as much natural light in as you can - raise blinds and open curtains in all rooms.
If the house is likely to sell to a family, get a list of local schools, and if they have good OFSED results you could print them off to give to the agent to pass on.
Good luck!