About primary lymphedema & disability?

I have lymphedema in both feet/legs now for 26 years. I live in the UK. My experiences with this condition is that it is not curable but treatable to control the condition. In the last 3 yrs I received my first set of treatments due to my own research for help. For those who unaware of what it is, it is swelling in the limbs caused insufficient lymph vessels to carry away lymph fluid. What I wanted to know is if this is regarded as a disability? Why GPs in the UK ignore primary lymphedema patients and if anyone knows of other advice I can get. I know there are many outside the UK. All recommendations will be taking into consideration. BTW my own GP is unhelpful. I want more direction.