Seating plan or no seating plan

Seating Plan is my nightmare, mainly as my mum has decided she should say who sits where and with who! We are not having the traditional top table as my Dad passed away and my future in laws are separated so don't want it to be awkward for them. We are having us, MOH, Best Man and our daughter and their daughter (our flowergirl) on our top table and then put families together but I honestly was happy to just have a load of table with a sign saying find a seat! For the style of wedding you are having I think it would be nice to just have a table for the 2 of you at the top so you can look out at your guests and then load of tables and let people pick somewhere to sit and eat as it is not a formal sit down meal. Regarding extra seats, i wouldn't as it then means there would be gaps, have enough for your numbers and then people will have to fill the spaces. good luck with whatever you do!