Hi gals, So, there must be heaps of information...

Hi gals, So, there must be heaps of information out there about this one, but I can't seem to find it. Basically, I want to introduce formula milk to my dd soon just for the day, so I can stop expressing at work (it drives me insane, no spare time and really quite exhausting). She takes the bottle really well, and has been doing really well at solids. So I expect combined feeding will be OK? Also, I'm weary of introducing formula because there is a bit of family history around lactose intolerance (My mum is lactose intolerant, and apparently I was on goats milk until I was 2 or so...). All opinions welcome please!