hang in there! I too am from the UK and yes I tend to agree that there doesnt seem to be a huge uptake in Wireless yet but I think maybe 802.11ac will change all that…who knows!
I would get a CWNA for sure if you are serious about being taken seriously as a wifi engineer. You learn a great deal about wifi and how it really works. Most vendors, like Cisco, will not go deep enough or far enough in wifi and just glare over things you really ought to know.
Im sure there will be an uptake soon in Wifi – IF and I do mean IF – CWNP becomes a pre-requisite for wifi jobs out there or at least desirable..