Hi,I'm Miranda, and I'll be happy to help you with your question.
After researching, I did find the relevant information for your friend to travel to Scotland at the UK Border Agency website: http://www.ukba.homeoffice.gov.uk/
From what I understand it looks like your friend will be considered as someone who is "visiting friends," which makes her a general visitor. According to the website, the "general visitor" category is for people who are nationals of countries outside of the European Economic Area (EEA) and Switzerland. Pakistan is not part of the EEA, which further confirms that the "general visitor" category is the right one for her.
Here is a link to the specific requirements your friend will have to prove to qualify as a general visitor: http://www.ukba.homeoffice.gov.uk/visas-immigration/visiting/general/requirements/
Now, your friend will have to apply for a visa to enter the UK because she is considered a "visa national" (Pakistan is on the list of countries that qualifies someone as a visa national). It is also suggested that individuals from Pakistan apply for their visa online at the UK Border Agency website. Your friend will probably want to apply for a short-term visa, which gives her clearance to visit the UK for a maximum of six months. It appears that the fee for a short-term general visitor visa is £80.
Here is a link to information on how to apply for a visa, and the page also has the relevant forms available for download: http://www.ukba.homeoffice.gov.uk/visas-immigration/visiting/general/apply/
Here are some other relevant links from the UK Border Agency website:
Different types of visitors: http://www.ukba.homeoffice.gov.uk/visas-immigration/visiting/
Specific information for general visitors (click on each question for more specific info): http://www.ukba.homeoffice.gov.uk/visas-immigration/visiting/general/
Documents a general visitor must show (if they are applying for a visa, these documents should be submitted with the visa application): http://www.ukba.homeoffice.gov.uk/visas-immigration/visiting/general/documents/
I hope that answered your question. If you have further questions, please ask. It's been my pleasure helping you. Please remember to rate my answer positively, as rating me is the only way I receive payment/credit for my work. If you would like to request my help in the future, please post your question with "For Miranda Only" at the beginning, and I will respond.