Podiatry would seem to be the easiest of the AHP's to get into fairly lucratuive private practice with. (biiiiiig investment in kit to go private though).
otherwise i suppose think carefully about doing the same job as your other half. Mrs julian and I both do 'mental' nursing (she works in on of my old teams with loads of my old colleagues/friends) and it is nice that we have no 'business' with each other in our day-to-day work; and 'interesting' when we do not see eye to eye!
Would you be looking particularly at physio if your mrs wasn't one? Have you considered that whatever qualifies you for physio probably also gets you into Occupational Therapy, Dietician-ing, Podiatry, possibly paramedic-ing and dare i say it nursing?
But university as a grownup isn't that bad particularly since in health related stuff, half your course will be 30's or over.
Bigger considerations will be financial side of it and distance of placements from your home: unless you do nursing or ambulancing, most universities seem to reserve the right to send you literally hundreds of miles away for your practice placements.