Hiya
good responses so far!
The places I've mentioned are NOT cities - they're way too small for that!
There is i'm sure a definitive answer but generally..
Uxbridge I'd say is a small/medium sized town, Iver is a village, Gerrards Cross and Beaconsfield small towns/villages, Denham a small town/village...
The fact they're all on the outskirts of London and very close to the 'borders' many people refer to them as 'on the outskirts' of London and or a 'small town/place just outside of london'
Definition wise - Ksand is correct, a place with a Cathedral is classed as a 'city'. Without and they're towns.
The 'County' in the UK is 'equivalent' (geographically) as a 'State' in the USA - for instance, I live in the County of Berkshire. Within that, are cities and towns (I'm sure Reading is a City?) - The word 'District' is also used although it's not definitive as such nowadays - I think it may related to local church districts as well as the more often heard Parish - someone with more knowledge may correct me there.
So generally, it goes 'UK, 4 countries, County, City/town, district/parish.
The 'Boroughs' are 'generally' used to identify areas in London and Greater London - Don't get confused with more far flung places such as Peterborough etc although I know 'borough' is used in many other towns/cities throughout the UK.
Hope all that is as clear as mud !
As for the apartment - 6 of you in a 2bedroom flat and I think you'll be really pushing it - you must remember, many 2bedroom flats/apartments here 'generally' have less square footage as many 1 bedroom apartments in the USA! I'd say with 6 of you - 4 who are growing and probably lively and active - a 3 bedroom house would be ideal and I guess at a push, a 2 bedroom house 'may' work out. Depending on the depth of your wallet, you will find places to suit and what I just said is no hard n fast rule!
I rent a 2bed apartment and I personally wouldn't rent it to a family with 6 occupants - even if the kiddies are small, you'd all quickly trip over each other and you'd have no where to put you're belongings -
unless of course you do find a large apartment! they do exist! a relative of mine has a 2bedroom apartment that he bought right away upon seeing the size of it !
You will need to really hunt these type of places down though! they're very rare!
Hope this helps !
Cheers! DtM! West London & Slough UK!