In a recent paper in Varsity, Bethan Clarke talks about the value of her experiences on an informal placement in the Steventon Lab during the summer between Part 1A and Part 1B.
She found that the work she did, though not directly related, contributed significantly to her Part II project [in Zoology]. And since she had aimed for lab experience specifically in order to determine whether a career in research was a suitable option, this cleared up any doubts she previously had.