Your post caught my attention with "varicose vein surgery". Prior to being diagnosed with MS, I had varicose vein surgery. Within a month of the surgery, I stubbed my toe and fell as I was taking a walking tour of Washington DC. This was probably the first sign of what was to become foot drop. When I was in post-op after the surgery, I asked my husband "What happened to me?" He replied "Nothing - why?" I had this very strong feeling that something went wrong in the surgery - it was five hours long. To this day, I think I was experiencing an MS attack during the surgery (even though I did not know I had MS) ---I knew something happened! Since that surgery, I have been extremely careful with any anthesetics.
You asked if anyone had problems with surgery - this is my personal experience. I do not intend to imply what happened to me, would happen to anyone else. IMHO you need to listen to your own body, to your experiences. If you decide on the surgery, be sure to check the amount of time you will be under the anesthetic, check the temperature of the operating room - check anything that you now know exacerbates your MS symptoms.
Just curious - have you tried some form of supplements or herbs to help with the varicose veins? JimmyLegs would be a great resource for you - send her a PM.