Multinational marriage / settlement issue

Tricky case here, hope to have some good feedback from members here!

Situation: I am a (male) Canadian-UK dual citizen. Last year I got married in the Philippines to a woman who also has a 7 year old child. I am now trying to get us settled in FRANCE, where I can reside as an EU national. The French require that our marriage certificate be validated in my "home" EU country. Problem is I have never lived in the UK, only Canada, Germany & France. The other tricky point is that on the certificate my nationality is listed as "Canadian". Does anyone know if it's possible to submit this certificate with relevant Canadian and UK ID (I have a UK passport) and from outside the UK to get the validation....and WHERE in the UK to submit it? Thanks all!

My only suggestion would be to contact the British High Commission/Embassy in France. I would assume they could validate it for you or at least advise you on the process.