FFP
I think I am right in saying that the OU has come top university in "Students' Satisfaction", voted for by actual students, for the last 2 years. My previous Electronic Engineering HND attracted 190 points towards a 360 point Honours BSc, I am currently plodding through 3rd year maths. 60 points a year is do-able but don't under estimate the commitment it requires, from you, your family and also to some extent your team at work. Personally 30 points a year is all I am willing to commit to. I don't think there are any comments above that I would disagree with. If you want to dip you toe in the water then start with a 10-point Level One course. If science is your thing, and it's been a while since your last period of study, try S151, Maths for Science. It costs £140 and starts 4 times a year.
One thing I would point out is that you can't study at your own pace in the true sense of the word. You have assignment dates to meet (there is a little bit of flexibility in some of these dates depending upon your tutor) and the exam is on a set date; get behind the published drag-curve at your peril.
Good luck - go for it.