ILR quesion

[Khadar]

Hi all,
Here is the background of my question:
A friend married to a British citizen came to the UK and he next week wants to apply for ILR after completing 2 years.His wife gets child benefit,working tax credit and child tax credit.However,he works full time and the wife also is on maternity leave and gets 50% of her pay. 1)Will these public funds affect the husband's application?
2) they lost the overseas marriage certificate, do they really need to submit it?
Many thanks