How does the R4 handle wet conditions? How long before I'm drenched?

It can take quite a lot of water before the rain gets in. Maybe drizzle for a few hours, or a 10 minute heavy rain storm. But if I thought it was going to rain I wouldn't take this jacket unless I was close to the trailhead. Instead I'd go for a non-windproof jacket (R2/R3) and carry a separate lightweight hard shell. If you're going to carry a hard shell anyway, there's no point in wearing two windproof layers - you'll sweat like a mofo and be carrying extra weight for no benefit. IMO, this jacket is awesome (I have one!) for drier conditions and unexpected rain of short duration.

I was wondering if some water repellent spray may help before going out somewhat similar to that used on suede shoes! I live in england where the weather is drizzly virtually 24/365 !!I

Honestly it does pretty well in wet conditions. The high pile fleece repels water really well, and is a fairly dense fabric to keep the moisture our, and the windproof membrane gives it a little something as well. A buddy of mine was out in dense wet snow all day, and by the end of the day it was just coming through the shoulder seams a bit. Definitely more to the R4 than your average fleece

Its similar to most others in that it'll shed a decent amount of light rain before it starts to absorb, but its still not a rain jacket. How long before you're drenched will depend on how heavy the rain is.