Mortage Loans Bad Credit

If your in a credit card debt of say £6,000, can you file for bankruptcy?
And what are the disadvantages of bankruptcy? i dont care abt getting another credit card, loans, car, mortage, etc, alos what other options are there if ur in credit debt of 6 grand & cant pay it off? what is the worst that can happen, ive been getting letters since 2001 & today got a post card saying i was not in so i will be contacted in this specific time, but i have never got back to them & dont belive i never will cuz i just cant pay it so am i entitled for filing bankrupt? if so how much does it cost here in the UK? £400?
http://www.iva-advice-online.co.uk/bankruptcy.html?OVRAW=declaring%20bankruptcy&OVKEY=declaring%20bankruptcy&OVMTC=standard&OVADID=5433824031&OVKWID=30562690531
http://www.moneytailor.co.uk/_ppc/bankruptcy.html
http://www.insolvency-advice.co.uk/?OVRAW=declaring%20bankruptcy&OVKEY=declaring%20bankruptcy&OVMTC=standard&OVADID=456225531&OVKWID=2291338031