Collectibility is subjective. What is highly collectible for some is of limited value to another. With this guide, I will list Beatle UK records which most collectors would agree are definetly worth adding to the collection.

• UK Please Please Me "Black & Gold" - The stereo version of the Black & Gold is pretty close to the Holy Grail of Beatle collecting. Especially if it is in very nice condition. The mono version is right behind it. Biggest issue when trying to secure this record is finding one that has not been played to death. Premium for a copy with the "Dick James" credits. Great alternative is the Australian version. The Aussie pressings look almost identical to the UK version and are well made and cheaper. Expect to open the wallet for the UK copies.
• UK Please Please Me "Yellow & Black" 3rd Pressing - this is the version with "first published in 1963" omitted from the label and the very first Y&B Beatle pressing. This label had a short shelf life. Soon afterwards the "first published" print was added and hence the 4th pressings came out which are far more abundant. Any stereo copies of the early Beatle LPs are worth more since mono was the norm back in the early to mid 60's. If you land a stereo 3rd pressing Y&B PPM you did well.
• UK With The Beatles Y&B with the "Jobete" credit for Money - the "Jobete" credit for the song Money denotes a very early pressing since this initial credit was incorrect and the labels were later changed to the correct credit which should have been "Dominion". Again stereo copies carry a  premium although you should not pass up a mono copy with the "Jobete" credit.
• UK Please Please Me or With The Beatles without the "Sold in the UK..." verbiage above the spindle hole. Pressings without the verbiage denote early pressings (circa 1963) for the Fab's first two UK releases.  Copies with the "Sold in the UK..." wording appeared in 1964 and although collectible are worth less than the labels without the text.
• Any stereo copy of the Beatles' first four UK releases - again because mono was the prevailing format at the time, stereo copies are worth more. The first four releases were: Please Please Me, With The Beatles, A Hard Days Night & Beatles For Sale.
• Any copy of the Beatles' first four UK releases with "The Parlophone Co. LTD..." printed along the label rim. Later pressings (starting in 1965) were changed to "The Gramophone Co. LTD...". Copies of the first four LPs with "The Parlophone Co. LTD..." are worth more than copies with the "Gramophone Co. LTD..." text. If you land one of the first four LPs with "The Parlophone Co. LTD..." text and it is a stereo copy, you should take your significant other out for dinner and have a toast.
• Any UK release that has a "1" etched in the dead wax at the 9 o'clock postion and a single alpha character at the 3 o'clock. The "1" indicates the record was pressed from the very first mother and the 3 o'clock represents the stamper number. Single characters at 3 o'clock indicate very early stampers. If the only letter at 3 o'clock is "G", and the mother at 9 o'clock is "1" you have yourself one of the first 300-500 pressings ever made of that record. That's a keeper my friends. For more information on decoding Parlophone records, please see my Parlophone Matrix, Mothers and Stampers guide.
  
• UK Revolver mono with the matrix ending in -1 on both side of the record. The matrix is located at the 6 o'clock position in the dead wax. This matrix combination (especially the -1 on side 2) represents the original "Tomorrow Never Knows" mix which John Lennon had pulled due to his dislike of that particular mix.
• UK Rubber Soul mono with the matrix ending in -1 on both sides. The matrix represents the "loud cut" pressing where the record plays louder than Parlophone specifications called for at the time. This is another pressing with a short shelf life. Parlophone corrected the pressing soon afterwards.
• UK Sgt Pepper mono - only because the mono version had the Beatles personally involved in the mix. With the stereo pressing, the Fabs left the mix to George Martin. Is the mono cut better than the stereo? It's up to the individual listener. Collectibility however is driven by the Beatles' direct involvement in the mix down and the continuing aura around Sgt Pepper in general. Side note: the mono copy is not as rare as folklore would like everyone to believe. There are plenty around.
• UK Sgt Pepper "Wide Spine" and "Fourth Proof" covers. Both covers had limited production and are collectible. "Wide Spines" is a reference to the spine on the LP jacket being wider than normal. "Fourth Proof" is the rare Garrod & Lofthouse flipback cover with "Fourth Proof" printed at the top of the gatefold (upper right hand side - above George's head).
• UK Sgt Pepper with the song "A Day In The Life" omitted from the label. Self-explanatory. Have to figure the guy that missed this one was soon looking for work.
• UK White Album mono - more a collectible in the United States since no mono copies were pressed by Apple in the US. My UK friends tell me that the mono copies are fairly plentiful in Great Britain. There are different mixes of the songs. Most notable is Helter Skelter. With this album you are looking for the top loading cover with the black inners, the original pictures,  the original poster and of course numbered (the lower the better). Nice copies go for a pretty good chunk of change (~$500).
• UK Yellow Submarine mono - this is collectible because not many were made but you need to be aware that the mono mix is not special. It is the exact same mix as the stereo version converted to mono. You can get the same playback by playing your stereo copy and pushing the mono button on your reciever.