The fact is the UK Russia bilateral is pretty restrictive in anycase .
Currently it just the vacant (ex Easyjet) LGW - MOS route available to a UK carrier.
All regional flying UK or Russia is subject to protracted government approvals and with current FCO and Russian relations these are unlikely forthcoming any time soon.
UK and Russian links (doggy Plutocrats excluded) aren’t that defined or indeed particularly numerous unlike those between Germany and Russia - these include significant VFR traffic flows.
Entry in Kaliningrad will be very heavily controlled - Its essentially a HUGE CiS military base in the middle of NATO territory today.
Again there will be NO extra and unusual schedules but some organised charters only, with prescient and previous history - How many scheduled operated to Sochi from the UK have guess !