barrmark - here is the summary of the rules in England and I don't think it is any different in Scotland so I think you will be fine.
* Under the age of 14 children are not permitted into the bar area of a pub unless the pub has a children's certificate. In this case they can enter if they are accompanied by an adult. This will, naturally, vary from pub to pub but doesn't affect you anyway.
* At 14 you can enter a bar or pub but only if the landlord agrees and if you drink soft drinks (this can include low-alcohol beer) - so always best to ask then for your 15 year old grandchild and tell him/her that just because he/her is in a pub does not mean he/her can imbibe!
* At 16 you can buy beer, cider or perry (made from pears) in a restaurant or eating area of a pub where there is no bar, if you are ordering a main meal.
* At 18 you can legally buy drinks in a pub, bar or off licence.
I don't think the rules (the ones barring under 16's) apply to the restaurant part of the pub if it is separate from the bar so you can take any age children for a meal if they are not in the bar area but of course best to check first with the landlord. I don't frankly think you will have any problem at all - they will just be delighted to have seven people coming in to spend money in their pub!