I hope your DD is getting much, much better.
Absolutely the police need to act. The potential impact of these crimes is horrific. There is the medical injury, plus whatever the perpetrator planned to do.
Surely CCTV, interviews, etc.
Landing someone in ITU alone should be at the top end of a crime that carries sentences of up to 10 years:
https://www.gov.uk/government/publications/understanding-and-tackling-spiking/report-understanding-and-tackling-spiking-accessible
Although some of the offences use archaic language and may not readily be identifiable as offences that ‘capture’ spiking behaviour, these existing offences can (and are) used to prosecute spiking crimes today, with some offences attracting maximum penalties of up to 10 years imprisonment. These include offences primarily focused on the harm caused, ranging from common assault and battery to grievous bodily harm (GBH), and their inchoate versions, for example attempting or conspiring to commit an offence. There are also offences that would cover spiking which are more prescriptive to how the harm is caused. These include sections 23 and 24 of the Offences Against the Person Act 1861 (“the 1861 Act”) and section 61 of the Sexual Offences Act 2003 (“the 2003 Act”).
Section 23 of the Offences Against the Person Act 1861- Maliciously administering poison, so as to endanger life or inflict grievous bodily harm. “Whoever shall unlawfully and maliciously administer to or cause to be administered to or taken by any other person any poison or other destructive or noxious thing, so as thereby to endanger the life of such person, or so as thereby to inflict upon such person any grievous bodily harm, shall be guilty of felony, any being convicted thereof shall be liable”
Section 24 of the Offences Against the Person Act 1861 - Maliciously administering poison with intent to injure, aggrieve, or annoy any other person. “Whosoever shall unlawfully and maliciously administer to or cause to be administered to or taken by any other person any poison or other destructive or noxious thing, with intent to injure, aggrieve, or annoy such person, shall be guilty of a misdemeanour, and being convicted thereof shall be liable”