Unconditional offer are rarely given and it’s mainly worked out based on how many people apply for that course at that university for that year so there’s no way to tell at all.
For conditional offers it really just depends, the D doesn’t look great but it depends on what they are asking for? Trying looking at the ucas points and working out what your predicted points are to get a better idea, if you meet the points and they like your personal statement they could ignore the D