If she is not sure who would come could she not just choose a large bar in the area and say to friends to come along if they are free. means she has not booked anything, so not sitting in a big empty place but if biggish crowd come along there is still room? Alternative is some places here in Glasgow do Cocktail Materclasses, am going to one for a hendo. She could just pick closer friends that she is more confident about them coming along and invite them. You normally would have to pay a deposit then you go along, get a cocktail demonstration (getting to mix a few yourself) then have a meal? Suggest some close friends go to a spa? I ended up having various things for my 40th but was more so cause people expected me to be doing stuff (not complaining though). When it came to family, I just went out for a nice meal with the immediate ones.