I was a size 18-20 before pregnancy too. My BMI was 34.17 with my first pregnancy, which unfortunately we had to terminate due to a not compatible with life diagnosis. I fell pregnant again and was 3 weeks further along at my booking appt, and my BMI worked out at 35.1. I mention this because they do consider the thresholds at 30-35 and 35+.
Anyway, I haven't found it a problem at all. I'm now 33 weeks and have never been weighed again since - I'm actually really amazed I've only put on 12lb so far. I was offered extra scans at 32 and 36 weeks, but no one has really said whether it was because of our previous history or purely down to weight and age (I'm 39).
I'm Consultant-led, but again, I've only had 2 appointments with her and she's been so lovely. It's been more about reassuring me about potential abnormalities than anything else, and if I'm still doing well at 36 weeks I can be downgraded to midwife led care for birth. I don't think this would have been offered if I hadn't asked, so don't be afraid to. It would have opened up the midwife led unit and pool etc to me.
I was given the GD test at 28 weeks and didn't have it.
I'm having a good pregnancy this time, I've not had any weight related problems and I've got a lovely round bump - I was sad at the thought about just looking chubbier but it's very obviously a baby!
Only thing I've found hard is getting maternity clothes in bigger sizes, I really need a 22 now and not much is available. I can recommend
George at Asda - pants, long vests, swimsuit, PJs, oversized shirts
Next - twin packs of leggings
Lovall - just got my first order from them, joggers, jeggings and tights in bigger sizes, wish I'd ordered sooner
Beyond Nine - Love my Poppy jumpsuits
Seraphine - have a few bits in bigger sizes in their Curve range (look on Vinted too)
Tu at Sainburys have a few bits too
New Look - I've got a few jumpers
H&M - ok but their clothes aren't my style, would be good for holiday clothing