I am just about to do my last two shifts as a student nurse, and turned 43 in July, so 38 is definitely not too old!
As I already had a first degree, the course I have done is a pre-registration Masters in Adult Nursing, which involved completing all the required 2300 practice hours in two years (so averaging 40 hour weeks on placement), and a faster start to the academic side (our first assignment, which was expected to be at graduate level, was due in the first term). This has been a stretch, and sometimes I have wished that I had taken the three-year BSc option! However, with a bit of commitment it has been totally do-able (now that the trauma of writing my dissertation has faded a bit!), and in many ways age has been an advantage. Sometimes life experience can really help in reading people and situations, and as much as the younger students wonder how I manage juggling home and study, I wonder how 18-year-olds cope with angry or distressed patients and difficult colleagues.
I was not the oldest student on either the MSc or BSc courses, and have managed to juggle studying and family commitments (I have two DSs aged 8 and 10) with the help of a very supportive husband, whose work was flexible enough to allow him to do childminder drop-offs and pick-ups while I was working long days. I have found that placements are mostly quite open to meeting students' needs with respect to working times (as long as you approach it in the right way) - especially as students with children are now paying for their education as well as childcare costs.
The Trust I have had placements with does long shifts (07:30 until 19:45 or 19:30 until 07:45), but also does early and late shifts during the day, so you would arrive for an 07:30 start and finish mid-afternoon, or start at around 11 and go on until 19:45. Shorter days are obviously a lot easier to manage childcare around, although you would do more of them in a week, which can be tricky if you are working on assignments at the same time. As far as nights go, you will be expected to do at least some, but most nurses are surprised to see students on night shifts so you may not need to do lots - I plan to start out on the ward so figure I might as well get used to it!
Placements may also be in settings other than hospitals, so shift patterns here will be different - I spent six weeks with the District Nurses, doing basically 9 'til 5 on weekdays, although they did also do lates (14:00 until 22:00) and weekends. Other students in my cohort have been placed in sexual health clinics, nursing homes and even a private hospital.
Anyway, if you decide to take the plunge, best of luck - there will certainly be times when you wonder what on earth you have got yourself into, but all you have to do is keep putting one foot in front of the other and in the end you will get there 