Hi Alvee,
Wot I dun woz... to get to a Ukulele taster session if possible where you can try out various different makes and models and sizes. If there arn't any of these ariund your area then hit the local music stores and try out their stuff.
Both options give you the chance to speak to other musicians who'll be able to answer all your questions - possibly better than the music store (my local specialises in guitars and often (to a bit of annoyance) say "its like a guitar...").
So try before you buy. Personally we went to a taster/workshop for an event in town and we played on these cheapy £16 things (cashconverters etc might be worth a look) and we thought that was great and soon bought a Lanakai for £60 from eBay having played with one in a "real" shop in Cardiff.
Music stores a great to try out as they have loads of WAY too expensive ones and some cheap n nasty ones so you can get the spectrum of price/quality/brand/size.
Start with a cheap (like my "[more spam]")to get the feel of it then when you feel you deserve better (and you do and will) look to get one of a higher quality.
The last thing you want to do is fork out £80+ for something thats too small or that sounds/feels not so great. See my sig for the 3 I've got, Cheap but good enough "'ol yellah", smoother louder LU51 (her's indoors) and my toy the Electro Acoustic & pedals.
GuitarPix made a reference to strings, I wouldnt worry about these yet (IMHO) until you're getting into pro territory. I guess they'll sound better but I'm yet to change my strings, I'm an "if it aint broke" kind of player.
Hope this helps, have fun "researching".
[b]Its in the name![/b]