Likewise, I'm going to feel this loss a lot. I'm an enormous fan of his work - something that I got from my father who'd loved the Karla trilogy (the three books that start with Tinker Tailor). When his last but one novel came out, I thought I'd go about trying to get a signed copy. So I went to Hatchards in Piccadilly, a very old bookshop that is renowned for being for the more discerning customer (it's actually owned by Waterstones these days, so it's an elaborate facade really). I wondered if they'd have signed copies so I went in on release day to pick one up if they had them. In front of me in the queue was a lady who was after the same. Sadly, the assistant told her, they didn't have any right now, but the author came in fairly regularly and signed what stock they had, so we should check back occasionally. (I managed to get a signed copy that same day in Foyles instead - London being lucky to still have a few good bookshops. It was pre-signed, I didn't get to meet him).
Overall I think Le Carré has been very well served in both TV and film. The Alec Guinness series are wonderful and I re-watch them every few years. Indeed I see that there are HD Blu-ray releases of the two Guinness series, so that could be something to get over the holidays. A Perfect Spy is also excellent, and is a very autobiographical book - his father was an interesting character, and not all the man you might imagine if you ever heard Le Carré speak.
The more recent series have also been very enjoyable. I thought The Little Drummer Girl was a very good take on the book, but The Night Manager was especially good with top performances all round.
There's also an excellent series of Smiley BBC Radio versions that you can probably find on Audible. They're well worth your time, with Simon Russell Beale, an actor who does appear on film and TV, but is most famous as a stage actor, playing Smiley.
Adam