In regards to the UK read this document very carefully:
https://www.gov.uk/government/public...dence-test-srt
You may well remain a tax resident in the UK even after leaving for Russia/France (if your a UK tax resident at the moment). I agree with the above post, stay well away from France!
As for Russia, think about this:
Tax rate
"Normally tax rate is 13 %, it is for resident. To be considered a Russian resident, residence must be established of at least 183 days in Russia during any calendar tax year. Non-residents are liable to tax a flat rate of 30 %, generally withheld at source. No deduction or allowances are available for non-resident."
So if you can prove that your really a resident of Russia, then your tax rate is very low (13%)! if not then its pretty standard by European terms!
These days if you reside in a country for tax purposes then you really have to prove it and countries such as the UK are increasingly focused on your centre of life. If your wife and children remain in the UK/France and you leave for Russia due to tax purposes, then expect to be investigated! Working for a UK company on a UK contract could make that difficult! HMRC have made successful claims against Pilots in the past!
If it looks too good to be true, then it probably is!
Do you really want to live in Russia? I guess St Petersburg would be ok :-)