Marigolds do well even in the most sunless of London summers, and I've even grown them in north-facing window-boxes, so yes, they'll do fine.

Although I'm in Zone 5 and generally have 99.44% of the time had great luck with Marigolds (they're one of my favorites), the only time I had difficulty with them was last year:

Situ:

Marigold petite yellow "Janie-something" as I recall.
South facing, but hard-packed section of topsoil next to foundation. Soil is good- not clay.
House section jutts out next to this area about 6 feet and blocks the morning sun. Sun hits it about 11am.
Likely the section is also protected from winds & such, so doesn't get much in the way of rainfall, either, so the topsoil just packs down & dries out.
Mulching didn't help.
They did VERY poorly, and when they were near-death, I resorted to moving them to a full-day sun area with better moisture to see if that would help. They performed much better after that.

Otherwise, I've had great luck with Marigolds always. Many varieties being tried out this year.

i planted them in a container and they are now sitting in the sun. crossing my fingers...