I don't know what nurses make these days, or what overtime opportunities would be available to supplement basic income. Would it be possible for the OP to complete training without any debt so that the take home was a bit less of a worry?
I can't say anything directly about the salary on offer since I do not fly commercially. I, like the OP, am someone who is looking at the career with interest and weighing up the practicalities.
Many of these practicalities which, whilst not being directly financial in themselves, will have a bearing on a trainee's bank balance. Will an employer allow 5-6 weeks of unpaid leave in order to complete an APS MCC-JOC course with an organisation that has good airline connections? What is the notice period on the NHS (some companies might want an immediate start)? After all, if it's not possible to maintain continuous employment throughout the training process, the living costs may start to add up very quickly. If the decision is made to quit one's job or industry, is it possible to return to it easily?
I would say not to only look at take home pay once qualified but to also consider how to make the training path itself work out financially.