I went to see a FS in Feb this year after my third (and traumatic) miscarriage, and saw the most horrible of consultants who tried to insinuate that my weight had caused the miscarriages and she wouldn't see give me clomid until I got my BMI below 30 because any further pregnancies would result in M/C as well because of my weight. Obviously this comment was crap and completely untrue but she DID send me away with metformin and whilst I didn't manage to conceive (or regulate my cycles at all - they got worse as I lost weight), I pushed myself to lose weight and I saw her again today with a BMI of 29.8 and she gave me clomid straight away.
My last m/c was not connected to weight at all but actually a rare condition, but I noticed a lot of consultants on the NHS are very quick to jump to try and pin it on weight. I also took clomid for the last pregnancy and ovulated exactly when I was supposed to - so once again my weight wasn't a factor in that, but she wasn't having any of it.
It's a load of crap if you ask me, as some hospitals have restrictions where they won't treat unless < 30, some under < 35, and some don't even really look at BMI at all. A friend who recommended this particular clinic to me was actually heavier than me and was never ordered to lose weight, so it's really down to who you see.
If you don't get offered any fertility treatment right away they might at least offer you provera/norethisterone to bring on an AF. Are you over 30? Do you know if you have PCOS? I think they're more likely to help you if you're near their BMI range if you're a bit older.. And metformin might be an option for you if you have PCOS.
Also, I think you have more leeway if you decide to go private. I remember reading a story on here before where a woman went on the NHS for treatment, was sent away with massive lectures about weight blahblahblah, and then came back and saw the same person privately and was given clomid immediately with no mention of her weight again.