Good idea, you can never have too many field guides - I have 14 at the moment :-)
These are my choices for anyone, not only a beginner, as the pictures and print are top quality, clear and easy to ubderstand.
1) RSPB Pocket BIRDS by Jonathan Elphick and John Woodward. Published by DK, which is the reason why it's number one.
2) Garden Birds of Britain & Europe by Detlef Singer. Published by Collins. Beautiful photos, 2-3 on each page plus thumbnail of eggs. Excellent book and only 156 pages so easily slipped into jacket.
3) Birds of Britain & Ireland by Dominic Couzens. (A Guide to Identification and Behaviour). Written by a man who is well respected and knows his subject, so no 'iffy' bits. More encompassing to include feeding, flying, nesting, pair bonding, climbing, hunting etc. but all written simply (for me to understand!) Another Collins publication. This is one to dip and really lose yourself in.
All 3 books are soft covered, but with wipe clean vinyl extra covers. I haven't put the prices as they've probably changed but all are under �10.