Women In Love is Lawrence's tour de force - a far better novel than, say, Lady Chatterley.
Women In Love follows on from The Rainbow (in narrative terms). Remember that the publication of The Rainbow had resulted in a prosecution for obscenity. You have to read Women In Love within that context.
Lawrence clearly wanted to take The Rainbow "one step further" ... but had to use poetic descriptions of both action, and environment. The readers would know what was going on, if they wanted to. But, likewise, Lawrence could easily point to the "filthy mind" of any detractors.
Women In Love is full of intensity ... the violence between Birkin and Hermione, the homosexual history of the sculptor Loerke, the catastrophic relationship between Gerald and Gugrun, Gerald's suicide scene.
If you are in any doubt as to which way to interpret scenes like yours, RB, I think there is little doubt that you should look for the most intense feasible interpretation. I am fairly confident that DHL envisaged Birkin giving Ursula a damn good seeing-to.
JJ x