Hey Jonny
I am russian and i can tell you that you will not "legally" work in Russia (99,9%) - it is very hard to acquire russian permission to work, you will have contract with some off-shore or European company, which is not under Russian legislation.
Russian pilots who are working for off-shore/European company just dont pay taxes at all... but it is not European style, so you can pay your taxes in U.K. probably...