A survivor of the 7 July bombings is the first to sue the government because she says she has been refused medical treatment on the NHS.
Ms Rhodes has been told her injuries are "cosmetic"
Beverli Rhodes, from Maidstone in Kent, was a passenger on the King's Cross train, and says she has been forced to travel overseas for help.
Her head was smashed against a pole by the blast, causing brain stem injury and post-traumatic stress.
The Home Office has said it will not comment on specific cases.
Ms Rhodes has been registered disabled since the attack. Her job before 7 July was to help assess London's vulnerability to a terrorist attack.
She told BBC London her post-traumatic stress meant she found it difficult to work.
"There are certain triggers... if a trigger comes about, you don't have much control over your body, the body goes into fright or flight, and you will automatically evacuate any excess material on board, which plainly means you will go the toilet," she says.
Scars on Ms Rhodes' face caused by the bomb are not covered by her medical insurance, and she says the only place where she can afford the treatment to be carried out is Thailand.
The NHS will not pay for the treatment, it says, because it is cosmetic.
"For me, personally, it is necessary because eventually one side of the face will I believe become completely concave... it will make it very difficult to chew."
Ms Rhodes hopes other survivors will come forward and ask the government for help to get treatment.
BBC London contacted the Home Office, who said they had paid out £6m so far to 264 survivors, and there were hundreds more of cases waiting to be heard .
The government has said there is no time limit for those seeking financial help.