Criminal record only a problem for the subset of businesses that care/check about that sort of thing, which is less than what others are saying (25 years experience in UK).

Over 60 and a junior programmer isn't easy, your salary expectations are possibly higher and your willingness to grind through problems is also probably lower, I know both of those would be the case for me, and mean no offence. So yes to be honest it will be a bit harder for you, however, its a job seekers market at present and with perseverance I don't doubt you'll find a job, and without that same grit you'd unlikely to last as professional engineer today anyways.

Most companies don't do all that leetcode stuff in UK, interviewing is still a pain though.