Finland would be quite "well" off, given that most damage would come from fallout and in 1980's Finland had extremely large reserve stocks of fuel and food combined with the fact that urban population had fallout shelters available. In 1988 the reserve stocks for all products were sufficient to guarantee normal state of living - without any imports or restrictions - for a six months. In case of coal, the reserve stocks were for 15 months with full level of use, in case of medical products 16 months of full use.
In addition, plans for alternate poroduction were fairly advanced. In case of energy the Finnish forestry industries would be more than able to replace all imports of coal for an indefinite period of time and probably could start (economically inefficient) production of biofuels enough for most critical military and logistics use before oil stocks would run out. For nuclear fuel (4 reactors) there was sufficient reserve fuel for couple of years at stock.
In case of feeding the population there were reserve stocks of food for a period of more than a year. After one year the the lack of potassium would cut the harvests for 15%. This effect could be canceled by cultivating more fields than during peacetime (approximately 10% of field area was kept as crisis time reserve and could be taken into use immediately) and by decreasing amount of meat and poultry production. Finland during 1980's, like rest of the industrial world, suffered rather from a overweight than malnutrition which should be also taken into account. Fisheries, berries, mushroom picking etc. would also significantly add into nutrition of Finnish population thanks for large scale land area available per population and the tendency of population to use all of these as a popular form of recreation.
The period of attack - February - is the best possible time of year for the attack from Finnish perspective. Fallout ash will be falling in over a layer of snow, meaning it will decay for a few months before melting down. In case of nuclear weapons destined for Finnish targets (which would include, I'd guess, refineries in Naantali and Loviisa) the snow cover will eliminate flash damage, reduce heat damage and prevent any large scale fires spreading outside refinery areas.
So, to cut it short, it might be that Finland would be best off of all the countries in Northern Hemisphere. A nuclear attack on Helsinki, the capital city, would change this somewhat but would be manageable thanks to ample reserve housing available, sturdy construction of Finnish housing and well spread infrastructure and finally by time of the year.
Only threat of British nuclear deterrence would keep Finns from dominating the Western Europe