If you are a UK citizen and have left the UK less than 3 yrs ago and currently don't reside in the EU (except Denmark) then you can declare BR in the UK.
You can either return to the UK (High Court in London) and declare BR yourself or appoint someone as a power of attorney.
I would recommend you contact Paul Johns at Reviva (see experts button on left hand side) he assists many non uk residents in filing for bankruptcy, and it would be worthwhile you having a chat with him.
Melanie Nicholas 29 years insolvency experience - 23 of which in the Insolvency Service - Insolvency Manager Jones Giles email me at melanienicholas@jonesgiles.co.uk telephone 01792 899996