18th October is a Sunday? Is this a church wedding?
Some thoughts, sorry bit random, brain dump.
To the OP, if you go this route, you'll need to think about the brief you give the photographer, what exactly you want, what sort of group shots, maybe a little advice on best place to take the shots if you know the location\venue well. Bride & groom, with either parents, with both, with friends etc
Wouldn't you like any other shots, during the ceremony, signing the register. Is this time and shots proposed strictly limited by budget?
If you expect a photographer to just turn up and shoot and handover shots, when would this be and how? Would you give media card to be handed over after the shoot, or want them delivered digitally somehow. Note: risk of loss of media card in the euphoria of the day, going on honeymoon etc.
What rights does the photographer have to the images, can they use them in their portfolio or do you want all copyright handed over as well.
As a photographer yourself, think about the photographer handing over the images. What if you don't like the shots, would you slag off the photographer on social media (all risk to the photographer?) What protection to the photographer would you propose, bearing in mind you propose to edit the images.
If money is tight and you think photography is something that can be cut back on, how about asking for this as a present rather than household gifts? Perhaps some guests could club together. Photography always seems to be an area people think they can scrimp on, but those moments are special.