Portable AC for Bedroom - How to Choose/Efficiency/Noisy?

[Nachtvlinder]

On Swears By, there's a few that I might consider but I'm not sure if they actually work effectively.

How does it work when the ventilating hose goes out the window, but the hot air coming in.
Doesn't that defeat the purpose?
Isn't it better for the the unit to raised higher so that you can feel the cold air at bed height?
Has anyone got one that they can recommend that isn't noisy (I'm a light sleeper) and what the daily electric running costs are, please?

My budget can stretch to £600. I want to get one in advance so that the next heatwave isn't going to kill me this time. I hear that here in the UK we're going to be experiencing more of them more regularly.

How about a ceiling fan - how does this compare?

We have a ceiling fan, doesn't look very modern like some you can get, it's like the ones you often see in houses in Spain on "A place in the sun " type thing.
We have it on low speed overnight and it gives a gentle breeze I would say, although if it's on high speed it's very breezy! It's very quiet on low speed, my dh said he'd replace it immediately if it broke.
We have thought about getting an ACU but the fan is enough for us.