I've listened to the audiobook a couple of times and I greatly enjoy it, I haven't done any structured history studying since my A-levels but I am always interested in learning more and concerned about accuracy!
If this is the wrong place to ask then I apologise, I've never posted here before.
I remember when that aired originally, I caught a few episodes here & there. It seemed okay but note that: A) Andrew Marr isn't a historian but a political journalist & 2) As with any overview there's a chance that key info may be accidently skipped or just misinterpreted, that last one even more so as Marr isn't a historian.
What areas interest you specifically? Perhaps I could give you reading suggestions or you're more than welcome to check out the subreddit book list for slightly more accurate works of scholarship.
N.B. This is just my opinion and it shouldn't discourage you from watching or reading Marr.