I recently got a moisturiser that is actually 98% aloe vera, it's organic too. I got it from Sainsburys of all places and so far has done a great job of relieving the itching and settling it down a bit.
Most cases of psoriasis are a lifetime thing so you have to work on making it bareable rather than trying to cure it, I have had mine for 15 years now and in the last year I have developed a new type of it all over my back (before it was just on my scalp) which looks like pink leopard spots! Unfortunately its just something you have to live with. Sunbeds are good but again won't cure it.
The only great remedy I have heard of is a trip to the dead sea, my nans friend had a bad case of psoriasis, she went to the dead sea, took a long soak in it every day for 2 weeks and her psoriasis completely vanished..... although it came back 2 years later, although after having it for 40 yrs I bet 2 yrs off was a great respite!
Oh the moisturiser is called 'JASON' Aloe vera 98% moisturising gel.