Hello Mandy
Some dermatologists will run all the tests for systemic lupus and also ask for your health history and so on. Otheres will refer to a rheumatologist for assessment of systemic involvement.
Since they are sure lupus is affecting your skin they should be talking about treatment ASAP. Don't let them fob you off - ask about checking for systemic involvement and insist on an early appointment with a rheumatologist. If they have already done some testing, find out what they have tested and what the results were. Make sure urine has been tested - the GP can do this and also do a full blood count and an ANA, which is the basic screening test. You can say that you are concerned about the possibility of systemic disease and you know you should be checked for it and don;t want to hang about waiting.
I think I may have said before that I can't see what practical difference it makes which UVA you are sensitive to, although it is an interesting academic study.
You should prepare a health history leaving nothing out even if it seems irrelevant to you and of course a list of more recent health problems.
Read through the two lists of diagnostic criteria to see what you can relate to.
When chronic health problems of close blood relatives is known that can be useful information too.
There is no reason why they shouldn't start treating you with Plaquenil the usual first medicine for both skin and systemic lupus. The skin should start showing improvement within a couple of months.
Soemtimes people with skin lupus have a variety of complaints like joint pains even when they have no blood work to support an SLE diagnosis. The Plaquenil helps to stop the disease worsening.
Don't forget that UV exposure is year round regardless of external temperature. One type, the UVA, comes through cloud cover too and some comes through windows. I have found a problem in the UK with the variability of the weather in the course of a day so I wear sun block all year round indoors and out, and take my hat with me.
You can get sunblocks on the NHS so ask your dermy to write to your GP recommending it. I like an Aussie one called sunsense. It is easy to wear and isn't visible.
Good Luck
Clare