There was just the one Loyalist terrorist attack in GB which was in Glasgow by, IIRC, the UVF.
You're quite correct in suggesting the Provos were much better known, especially as they carried out terrorist attacks in Northern Ireland, Great Britain, West Germany and attempted to do so in Gibraltar.
They were also the world's most dangerous terrorist organisation for pretty much all of it, so it's hardly surprising they get the vast majority of the attention.
Another reason is this:
"There is not a single injustice in Northern Ireland today that justifies the taking of a single human life.
What is more, the vast majority of the major injustices suffered not only by the Nationalist community but by the whole community are direct consequences of the IRA campaign.
If I were to lead a civil rights campaign in Northern Ireland today, the main target would be the IRA.
It is they who carry out the greatest infringements of human and civil rights, with their murders and bombings, their executions without trial, their kneecappings and punishment shootings.
The most fundamental human right is the right to life. Who in Northern Ireland takes the most human lives?"
Those are the words of the leader of the biggest Nationalist party throughout the Troubles and who jointly won a Nobel Peace Prize with David Trimble.
John Hume. He was right too. BTW, there's video footage of him saying this as well.
It cannot be a mystery to any reasonable minded person exactly why the Provisionals (Provisional Sinn Féin and Provisional IRA) are the single most focused on group....