Where do i start arranging ..
Work out your budget first and then find your venue. Check with the registrar that they are available that day and then book both the venue & registrar together so you have the two hugely important things done. After that it's up to you but I would advise booking a photographer early as the good ones are booked well in advance. Hope that gives you a starting point?
A date .. That fits with being able to save a reasonable budget x
Date, budget and venue is a good start