Hold off on puting Revell on your blacklist, duckman.
If the Lancaster you're talking about is the kit I think it is (1/72 scale, moving contol surfaces, retracting landing gear and opening and closing bomb bay) then you have to know that the kit is positively ancient (we're talking nearly a fossil here).
I built it once when I was a kid, the above mentioned moving parts were typical sales gimmicks in kits years ago and raised rivet detail so overdone that you could use the kit parts for sanding blocks are another give away to the kit's age.
I thought that kit had been out of production for ages, the last time I clearly remember it showing up on hobby shop shelves was on a very limited basis in the mid 1980s.
Don't let this old kit form your opinion of Revell today, its NOT indicative of their current product line quality.
As for the Airfix Lancaster, I can't really say. If its a new release it should be alright if its just a reboxing of older stuff, who knows. Airfix is generally O.K. stuff, but largely middle of the road in quality in most things these days.