Definitely try for a dermatologist referral and UV therapy... it works a treat - but I'll tell you my story.
Rocked up at hospital for UV therapy.. directed into a side cubicle to take off all my clothes, put on a gown then come into the main room. Once in the room I had to de-robe and be assessed. Bit weird (British obvs) but then they assessed what "blast' I needed.
Entered into something akin to an upright tanning bed/Dr Who set... Had to stand butt naked and put my arms into straps hanging from ceiling.
Had a short blast and was sent on my way.
My treatment was twice a week and the blast I got each week increased a little bit - at its most it was a couple of minutes I think.
Now, I tan easily.
On about treatment 10, the nurses noticed my tan developing. Particularly on my face where (at that time) I had no psoriasis.
"oh" they say "we need to protect your face". "Damn" I think "I was enjoying my NHS tan".
Off they pop and return with what looks like a rectangle of flexible perspex. "We'll make a mask for your face so it doesn't get any more UV rays" they say.
Like odd party balloon shapers they start about fixing the flexible perspex. I, in my naivety, expect a welders type mask.
No, I am handed what can only be described as a mouse head mask complete with pointy nose
I place perspex mouse head mask over mine, enter the tanning cubicle, stand, as always, legs akimbo and hands in stirrups above my head and wonder whether the NHS is running some sort of niche porn channel as a means to bolster their funding 
In good news though my psoriasis disappeared.. I still live in fear of my naked mouse masked body appearing on the internet.
But seriously, do try to get a dermatology appt (but run for the hills if you hear perspex being flexed)