First of all congratulations. my elder brother just got married a while ago and luckily i had to arrange everything with my parents. First suggestion would be to definitely go for a hall, lahore in this season for outdoor weddings is a big no. The weather is unpredictable. Secondly your lawn is beautiful and spacious too, but not big enough for this function keeping everything in mind such as a stage, chairs, walking space and so on. Finalise that ur going for a hall.
Secondly deciding for a hall. I know a couple of really good halls, resonable, decent, they provide catering, food, decor and everything related.
My brothers walima, which was from our side, took place in Garrison Golf Country Club. They have over eight halls of different capacity and decor. The rent was pretty reasonable for the hall. They provided us with food from Hanif Rajput and if im not wrong, it costed per person around 700-800. The food was delicious. Variety of everything and of your choice. They also provide you with decor, they show you different samples on a laptop and you select from them. If i was in your place i would've gone for Garrison golf country club eyes closed.
Another good option is defence club, main j block club or sector clubs. The main club has almost around 3 halls. They also provide with each and everything from food, decorations, stage and so on. There halls are a bit out-dated but are really good for a small function like yours. They're food is also good, but i would say not as good as Garrison Golf Country club.
Another hall we surveyed was Services club pearl hall. It is a beautiful hall but a bit on the larger side size wise. They provide with everything aswell. Food is really good. Decor is good and so is everything else. Services club also has new halls, dont knw abt them. Cost wise it is a really good option.
My brothers mehndi took place in Jasmine garden defence next to dha security office. Beautiful place it is. Loved the setup and everything. BUT it is a garden, outdoor, not a hall. They provide with all the things A-Z and their work is outstanding. Food, decor, arrangement and everything.
I can provide you with cost figures of what we had arranged if u want for garrsion and jasmine garden.
My ipads battery is about to die. will check on this thread again. And please let me knw if u have any other question.
And one very important suggestion, enjoy the the function as it will be a big day for your family and sister. dont keep urself in a tight budget and spend a bit more and enjoy the day