Not sure if I am putting 2 nad 2 together and getting 5 !!

I have got a copy of a marriage certificate but the Fathers name is blank, only a line drawn through it. So has the Rank/profession of the spouse.

I am also struggling to find a birth record on FMP and Free BMD. Would this be a good indicator for illegitimacy?

Any advice would be helpful, as a beginner, this is the first time I have come accross this.

Thanks

Iain