I was given the Red album, the Blue album and Yellow Submarine for Christmas in 1976 when I was 9. My aunt had bought them second hand and I played them non-stop on my really crappy record player.
I used to listen to YS a lot back then (well, I only had three albums!!) and it never struck me as strange that side 2 was all orchestral music. I would play the March of the Meanies song especially loud because it used to scare my younger brother (I now feel guilty about being so cruel!)
The first record I bought myself was the Hollywood Bowl LP in 1977. I used to spend ages looking at the inner sleeve which had all the other Beatles LPs listed, with the song titles. I could list the tracks on every Beatles album, in the right running order, long before I'd even heard the albums!!
I then bought all the other LPs over the next few years - the two-box EMI pressings - and I got the box set of singles as a present from the same aunt who'd bought my original 3 LPs. I still have all my old records and play them to this day.
It was years before I actually spent money on any record that wasn't the Beatles - I think it was probably the Rolled Gold compilation by the Stones.