I've thought about the Microwave sized Window AC units that you see all over the US (and other countries) but you're right Paul, they're not really available, plus it's a hassle to install them, they look downright ugly from the outside plus dont really have much capacity (especially for the room sizes we have)
I've spoken to a few AC engineers and the ones you see nowadays in B&Q home depot and even on eBay are satisfactory units, it's the 'installation' which is important. I got a quote for a 10KW/h ( i think thats the units!!) split AC unit to go in our large living room. The unit itself was £400 odd, and the fitter wanted something like £350ish to fit it. Haven't gone ahead with it yet, we've just got our new conservatory (yippy! after ALOT of hassle with the company) and I bought a portable unit for there.
I also saw the 'Air Coolers' at B&Q and I can tell you these type of units work well! In India 'most' homes will have a 'Cooler' and although not as comfortable as AC it certainly is a great help. So if they work in June 48 degrees celsius (sp?) temps in India, i'm sure they'll work in barely reaching 28 degrees for a couple days in UK summer!
Dehumidifiers aren't really a solution to what Aeonix has mentioned as the domestic units are mainly for moisture removal - there isn't any perceptible air movement.
however, by using a AC unit for personal cooling and comfort (sleeping) and a dehumidifier for moisture removal after clothes washing and bathing and cooking - you should find an overall greater feeling of comfort.
Cheers! Dennis! West London UK!!