Not entitled to IVF

I'm 33 and my fiancé is 34. We've been ttc for a year and a half now. We've both been tested, turns out his sperm count is low and so is his motility. My fiancé has a son from a previous relationship. But, our doctor has basically told us that there is no help available from this point because the NHS won't offer IVF if one of us has a child from a previous relationship. We both desperately want children but just can't afford £5-6k a pop for private treatment. Gutted. 😢😢😢