A lot of people I know, and a lot of friends of mine in the UK have just had one joint event. Doing the whole separate dinner thing isn’t a big deal anymore.
Three months is doable but prepare to compromise. Eg on your outfit, might be quicker to buy ready-made than get it designed. If you’re on the ball you can get it done. Main stuff is Hall hire and caterers anyway, the rest can be done in that time.
Are you getting married in UK or Pakistan?