The ascot is probably a silk scarf. The British wore them to cut down on friction on the back of their necks. I don't think they were issue, so in theory could be any color, but I would bet on it being khaki or brown or something similarly subdued. They might well be in regimental colors. The beret would depend on the regiment or corps affiliation. One of the units that the kit has markings for is the 13th/18 Hussars. Being cavalry, they probably wouldn't wear the black Royal Armored Corps beret. I'm at work right now, so I don't know what unit the other markings are for. I'll check when I get home this afternoon. I may have a book or two that might have some info. If nobody else answers, I'll post whatever I find.
You're already at that stage? I have done most of the hull and turret, just the small fittings and the running gear to do there, and the painting. The links are taking a lot of time. Right now they are the bottle neck. Thank God my next two builds will be Tamiyas with rubber band tracks!