Yes, CDM, Marital Rape is certainly grounds for divorce in the UK. Not only this, but a wife can bring legal charges against her husband, and if found guilty he will be punished by the Law.
Marital Rape is an offence, and is punishable by a cuatodial sentence.
The law does not look kindly on rape, and treats marital rape as an extremely serious offence.
Of course, first of all the wife has to feel emotionally strong enough to complain and to bring charges....