Best degree leading to Astrophysics Masters

I'm hoping to study Astrophysics at a masters level once completing my undergraduate degree. I'd love to study it now as a first degree, but i don't think they offer it distance learning. I know the masters won't be distance however i'd be more able at that stage to look at a brick university (in a few years, for a second degree/masters/ect.) than I am now due to personal circumstance.

I'm still in the process of choosing/researching which undergraduate degree to take on the OU. I want to make sure I choose the right degree now, so as to lead to having the right entry requirements later. I'm a bit lost as to where to start. I'd be classified as a mature student which is also partially why i'm studying OU (at the age of 24.) I'm completely starting fresh essentially. I've been studying maths A level textbooks to make sure my maths is up to scratch as well. Willing to do any and all extra work I can do to get me into the right courses later.

I've been looking at:
BSc (Honours) Natural Sciences (Physics)
or
BSc (Honours) Natural Sciences (Astronomy and Planetary Science)

I'm not really sure what you're asking. You could do a master's degree with either of those degrees, although I think the latter would be best if you're interested in pursuing astrophysics. I believe the University of Central Lancashire does a distance learning Astronomy degree, if that's of any interest: https://www.studyastronomy.com/courses.php?id=1