English Universities determine their own academic dress as they wish, but almost inevitably, choose to ape the traditions of Oxbridge, with robes, hoods, and other such foolishness much in evidence. One notable possible exception is Newcastle-upon-Tyne, who, judging by the dress of Professor Peter Henderson in the 2003 Southampton graduation photographs, have a suit-based formal dress.
Who cares?
It rather depends on the institution: I am reliably informed that many
Cambridge colleges have various formal events (such as "formal hall" dinners) at which wearing a robe is mandatory, making ownership of appropriate undergraduate dress practically essential. By contrast, at Southampton, one never wears such dress except to participate in the
graduation ceremonies, thus guaranteeing that no-one really cares what the dress is, as long as they look as good as the people around them, a fact that the official robemakers viciously exploited this year by lending graduating masters in the
School of Electronics and Computer Science the same robes as bachelors. Although many people noticed, this author knows of no-one who bought their own robe.