Originally Posted by
corporate-wage-slave
And to be a bit more precise.
A return First RFS to Moscow is £55 plus 60k Avios. You can do it for a bit less, if you return to the UK in CW, WTP or WT.
The Russian visa, if you sort it out yourself with the consulate's handlers, VFS, will be about £85 for UK citizens. You will need an invitation letter too, which the more upscale hotels will provide for free so long as you pay to stay in their establishment.
Or you can transit without a visa and come straight back.