You can catch socks on fly without flossing them, but you have to search for clear water which is tough to find on the Fraser, otherwise you will have to floss them. Trouble is, where you find good flossing water, you will find lots and lots of people 'ing and they will not be pleased to see you swinging flys and there would be lots of tangles etc.
You are a little early for all the other species, although I caught my fist chum of the season today, which is very early.
Your best bests are as follows:
Keep trying Ambleside for Coho. You would have been a little early in July. You will have a better chance now as more fish stack up. Keep trying until it start to rain heavily, then fish the cap, but you have to be ultra early to beat the crowds (as in at least 1 hour before sunrise).
Explore the Fraser and its tributaries and try and find some clear water to try for Socks.
Mid to late September try for Coho, Chinook in the Vedder, followed soon after by Chum.
Late September, the Squamish becomes a good option again for Coho and Chum with less fisherman, because it's mostly catch and release.
The Stave is a great place to try for Chum in October and coho are also caught there (again go very early for the coho)
I hope you have a robust fly rod, chum can be beasts ( I hope you have at least an 8 wt).