Oi reckons the first step be to work out who's from the UK, and take it from there. Oi've spotted a couple o' "I'm from the UK" threads ('ere and
'ere), and o' course thar be the location on the profile. Based on these sources, here be the list o' UK FSMists:
Scotland
sakura
frog51, Edinburgh
Captain Pugwash, Dundee
AndyG, Dunfermline
Orys, Edynburg, Szkocja
Northern Ireland
Gray, Belfast
spacemonkeyman, belfast
polly, Belfast
Wales
President of Wales
pit monkey, cardiff
afteryoudieyoucrpyourself, Swansea
England
stupid, Worcester
Lewis, Lincoln
Rincewind SW, Sheffield
Near-life Experience, Oxfordshire
Altogether Isi, Oxford
bigscience, Oxford/Frederick
LNM, NW England
Fizzybrain, West mids
BiggerGoat, Manchester
kged, Manchester
George, Manchester
IkeAramba, London
ottovs, London
Onemeatball, London
and then, London
Benedict, London
sanctioning, London
Johnny Blood, London
Griffin, London
MexicanPirate, Lincoln
PastorPasta, Kent
theholyllama, Hull
drew, Hants
Drake Dragonslayer
Moony, Cambs/West Midlands
Stex
Vapour
GilesM, Derbyshire
syzygy, Bristol
Stronty Girl, Bristol
BettyHill, Brighton
mikes, North (Lancs/Yorks)
swarfmonkey, Warrington/North West
MikeyPB, Bognor
mikes, East Yorkshire
Bod, Milton Keynes
rickyroma, Leicester
w1zeman, Warwickshire
amenabletopasta, West Midlands
beagle, Cambridge/Newmarket
CunningLinguine, West Country
Anarcus, Manchester
Nick Jordan, London
The Librarian, Hampshire
Occam, Manchester
all'arrabbiata, Birmingham
jwalkland, Bradford
prolific8, Hemel Hempstead
Smee, West Midlands
Stibby
Consternation, Chatham
NIH Protected, Northampton
bet1, Shipley (nr Bradford)
ThegoodshipNoodle, York
The Black Spot, Middlesex
Black Bart
walktheplank
Tickle, Gloucester
Pachyderm, Birmingham
Goat Starer, Shipley near Bradford
Ezkerraldean, Ross-on-Wye
The Black Pigs First Mate, Middlesbrough
Weird beard, Southport
Adelbert, Leeds (W Yorks) half the time/half year in Oxford
paradox911, Nr Bedford
Shellra, Newcastle
UK
freddie
garethw
Mr Flibble
B Olognese
Bollynaze
langdona
rickyroma
eddy
deadgenome
Republic of Ireland
Irish Noodle
Oi thought Oi'd better list people in their individual countries in case there's a desire to 'ave separate FSM chapters (Oi listed the nations in order o' the quality of the national side's recent football performances

Please post a reply if ye'd like to be added to/removed from the list, if ye'd like an ammendment to be made, or if ye've got any comments/suggestions. Oi'm not sure that this list thing is a good idea, so let me know what ye think...

I am a noodle-ist
I'm an FSMist
Don’t know what I want but
I know how to get it
I wanna digest the pasta strings cos I...
I wanna be noodley!
The only way to be!
P.S. The Republic of Ireland category be added at the request o' the Irish Noodle. We be knowing it don't be in the UK, but His Exalted Aerial Pastariness don't be concerned by silly things like borders.
Edits:
-Added beagle's location.
-Added Moony's location.
-Added CunningLinguine.
-Added Anarcus.
-Added Nick Jordan and The Librarian.
-I added Occam, all'arrabbiata and Irish Noodle, and had to add a category for that. You may need to re-edit. DD
-Thank ye Auntie.
-Added jwalkland.
-Added prolific8, Smee, Consternation and Stibby
-Added NIH Protected and bet1
-Added ThegoodshipNoodle
-Added The Black Spot
-Added Tickle and AndyG
-Added afteryoudieyoucrpyourself and Pachyderm
-Added Griffin
-Added Black Bart
-Added walktheplank
-Added Eddy
-Added Goat Starer
-Added Ezkerraldean
-Added The Black Pigs First Mate
-Added Weird beard
-Added Orys
-Added Adelbert
-Added paradox911
-Added Shellra
-Added deadgenome
-Added polly