Hormone treatment for hypothyroidism is provided free by the NHS in the UK [1]. I'm not sure about the conditions that migrants to the UK have to satisfy to qualify for non-emergency treatment though.

(I am not a doctor, the following does no constitute medical advice, etc)

Hypothyroidism is a life-long condition, so you need to get your medication sorted out asap. Someone close to me has this condition, so I know from their experience that determining the right dose can be difficult, even with the help of blood tests and a doctor / endocrinologist. Be cautious about trying to do this yourself, although I appreciate you may have little choice.

Finally, T4 is not usually prescribed in the UK because it has limited effect. Nevertheless some people claim it helps them in combination and they often obtain it privately from Mexico. The same may be true for synthetic T3, which is the conventional treatment. If you do this then be extremely careful.

Good luck.

[1] http://www.thyroiduk.org.uk/tuk/NHS_Information/prescription...