Of course, in real life, support for the SNP collapsed in 1979 and didn't really return as a major force until devolution was achieved in 1999. The Nationalists were also profoundly anti-EEC at the time and Scotland delivered the largest "No" votes in the 1975 referendum. How times change...
I think Labour this time to keep in mind the actual increase in support it got in Scotland in '79 as contrasted with the rest of the country. An Assembly during Thatcherism will be extremely interesting.
Looking through the election results in the 70s, it appears that the SNP only started moving backwards following the motion of no confidence vote in the Callaghan government. In the regional and district elections in 1977 & 78, they were over 20% - compared to only 12% in both from 1974. The fact that this timeline delivered the Scottish Assembly, the SNP wouldn't have withdrawn their support in the Labour government of the time and any no confidence vote would've failed. Additionally, the Scottish Parliament gave them a platform to become a major party in Scotland, as they became the main opposition - so it's possible that this timeline could benefit them in a similar way.
The SNP were anti-EEC until the election of Salmond as leader in 1990. He was the big pusher of 'independence in Europe'; around this time support for independence was in the mid-30s - with about 75% of those people supporting EEC membership for an independent Scotland. In March 1979, support for independence was at only 14%.
It will be interesting to see how this develops during the Thatcher years; it's possible that the Assembly could reduce the collapse of the Tories, due to a different identity north of the border. Their opposition to devolution in the 80s and 90s eventually led to the wipeout of 1997 - whereas in this timeline devolution has already been delivered. That being said, Thatcher did get rid of the Greater London Council, so it's possible that we could see a Tory manifesto in one of these elections with a pledge to get rid of the Assembly.
Additionally, if Labour perform poorly in charge of the Assembly, it could benefit the other parties - causing a shift in Scottish politics. Also, the creation of the SDP in 1981 could see their support move away.