Is that definitely right, the corbyloon, about rounding of holidays? I know employers musn't round down when calculating statutory minimum holidays but I wasn't aware that there were the rules about rounding where a company's holiday provisions exceed the minimum. I recall there was some debate about rounding up/down of consolidated holiday pay for agency staff and I thought that some do round down.
Anyway, this makes me wonder whether the company will also want to factor in statutory holidays in to the calculation. They may say your annual entitlement is 27+8 (or 9 this year maybe) =35 (or 36), then scale it down based on 42/52 weeks and then deduct out how many days you have taken (maybe 19+7=26).
Also, I think some companies, rightly or wrongly, calculate entitlements based on complete months only, so you may not be given an entitlement for October. Again I know they can't do that when calculating the statutory minimum but I don't think that applies here.
Anyway, your employer should know.