She thinks she is a 'freak' because she isn't one of 'them'.
She calls herself a 'half-caste' then tells him about her mother crying in the pub because 'we could sing better songs than these'.
As Rita progresses she changes - note how Denny reacts and how she says of herself 'she's gone (her former self) and I've taken her place'.
As she says the course is 'providing her with life', but ironically it is also taking her old life away from her. When she doesn't turn up for the party at Franks we can see how she is beginning to reject her former self -she doesn't want to be a 'court jester', or 'good for a laugh'.
Frank knows that there is 'nothing of you' in the essay she does on Blake, but ironically it will get a'good mark' in the exam.
She is now a 'real' student, but not, in Frank's eyes, the 'real' woman she was.
It is a conscious choice for her, though and she is determined to have her place in the world she has chosen.
At the beginning of the play she is literally 'uneducated' - unschooled - knows little about academic things but LOTS about life.
(If you have time, read Shaw's 'Pygmalion' and see what happens to Eliza Doolittle when she comes under the influence of Professor Higgins)When Rita says culture is a 'way of living', she latches on to a really important fact about how people live.
(look at page 194/5) That's what 'education' is really about - finding things out and having 'meaning' in your life as a result.