SO very well done for beating that pernicious disease - more power to your elbow and completely understandable that you have a different outlook on life and different ambitions.
As we're the same age, I trust that what I'm going to say will not be misconstrued .... Your first step must be the Class 1 medical. Call them at Gatwick and explain the cancer to them. It may well be a bar but you will find them helpful and may require your medical records. Secondly, us oldies can have other things go wrong with our bodies which we might not be aware of; hearing, eyesight, etc.
Secondly, if it's the airlines you're after, you might find an element of ageism. The perception could well be that someone of our years may not be prepared to work for a second officer's salary nor be prepared to work with a captain who could be younger. However, maturity will likely be an advantage for instructing or working for smaller operators in charter/VIP work etc.
As I'm sure you've worked out, there is not a lot of work out there but, if you are going to fly anyway using your PPL, the marginal cost of the exams and instruction for the CPL course will not be that great. While you're doing the hour building, try to make as many contacts as possible; it's more likely that you'd get work through word of mouth and networking when it comes to the smaller operators.
Only you know your finances si I would recommend you start costing the flight training and work out the minimum income you would whilst a) training and b) as a salary. I'm guessing that you have another career on which you can fall back.
Basically, I reckon it's do-able but it won't be easy in this economic climate.
Cheers
Whirls