Apprentices are contracted to work 30 hours per week. There may be opportunities for further hours if you are progressing well with your training and can demonstrate you are working as a competent technician.
Working as a technician involves working some unusual hours; you may be starting very early or finishing very late, when public transport is not operating. Get ins and get outs may take place over night, for example. It is crucial you are able to attend these as part of your training, as there is a great deal to learn from getting in or taking down a show, so you should expect to work outside normal office hours every week. This is definitely not a 9-5 job!