@Zazz101 I have run a holiday let business for nearly 30 years and have been on the periphery of pretty much every possible human joy and sadness.
While it's nice to do a little extra something, you don't want to do anything super-special that's mentioned in a review. Unfortunately there are some chancers around who will fake a terminal illness if they get wind of a host who gives them a freebie/provides restaurant vouchers/does a million other kind things. Even if you just bake a special cake and one guest mentions it in a review, you then get five other guests saying "but I booked it only because then review said I'd get a special home-baked cake". That kind of thing.
In your position, I would probably do a few extras - a particularly nice/festive bunch of flowers, perhaps, and 'better' goodies than usual (I provide tea, coffee, hot choc, biscuits etc - but in that situation tend to upgrade all of these, but not so much that it sets up unrealistic expectations for future guests).
I wouldn't go overboard with decorations - just do whatever you normally do (I tend to go for neutral and tasteful, and not too many of them).
Leaving aside the practicalities of reviews and such like: my experience of guests is that the overwhelming majority (99.9% of them) want to be left to their own devices. They want to come in to a property that is warm, welcoming and - above all - spotlessly clean. Then they want there to be functioning wifi. They like tea and coffee and biscuits. They do not like fuss - and in my experience, this goes for guests who are ill.
It's also the case that home-made things can be problematic, as some guests have allergies and need an ingredients list - so while it's a lovely idea, it's not one that everyone appreciates. An entire meal would be massively overstepping, quite apart from being a minefield if, say, every guest went down with food poisoning.
Alcohol has also become a tricky issue as hosts who provide a free bottle of wine are supposed to be licensed to serve alcohol.
This might be useful to you, @Zazz101: https://www.pascuk.co.uk/wp-content/uploads/2021/09/Welcome-Hampers-PASC-UK-Sept-21.pdf
Basically, make sure your house is 100% clean, warm and welcoming, and make it clear to the guests that they can contact you at any time, should they need anything. And then let them get on with it.
(If you were to go down the 'free stay' route, which I have never done because I couldn't afford to, then do it in the form of a refund well after they have written their review!)