There are just short of 50 Embassies, Consulates and High Commissions in London, so there is a good chance that your country's will be amongst them.
Part of their remit is to look after and preserve your interests whilst you are in UK. Lack of space prevents a complete listing but the telephone directory will help you there.
Should you travel round UK most of the major countries have a diplomatic presence in the leading cities. In theory you are entitled to seek sanctuary in your country's little bit of UK, but if you were driven to such lengths it is likely that the nature of your offence would be such as to make officialdom unlikely to resist a request for your collar to be felt.
Stay cool, stay clean.
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