Is military service in Russia required with dual citizenship?

I have British and Russian citizenship and passport. When I go to Russia on my Russian passport there I am no longer British but Russian and likewise in Britain.

Under Russian law, you are required to do military or alternative service when you are 18. Say if I travelled there when I am 18 or over would I still be called up to do service?

As there I am Russian. Could I go to the British embassy while there and ask for help?