I think it's good that it isn't for a week as it gives him chance to settle in at your home and feel familiar, before any op he might have (hopefully it won't be anything too major). Which means after the op he'll be glad to be back in his familiar smelling cage that he has just got used to
Normally it's suggested not to clean anything in the cage for the first two weeks, while they are settling in and scent-marking - apart from spot cleaning the pee corner (using a potty litter tray can help there
. And leaving his nest in tact is a good idea too. If it isn't pee'd in it should be fine.
Although if he does have to have a little operation, rather than say just an abscess drained, he might need a clean cage to go back to in a week's time. In that case you could just change the substrate and sprinkle a bit of his old substrate on top so it still smells familiar - while not cleaning toys and wheel, so it isn't all smelling different at once.
For now I would just let him settle in his cage and carry on as normal. So he settles in and feels familiar before his op.
I don't know how you'd feel about this, but you could also possibly ask for another opinion on the lump (I noticed Souffle mentioned a vet near you). Although it would mean paying for a consultation and possibly treatment, it might give you a firmer answer up front as to what he thinks it could be, or what might need doing if he's a hamster specialist. Also you'll be taking the hamster home with you straight away afterwards.
Are pets at home intending to keep him there after the operation?
We had to take our hammy to the vets a couple of times recently. I was surprised at the cost which was less than I expected. The first consultation was £20, which included a thorough check and some medication. The second one, at a different vet, was less than £17 and included having his teeth clipped and some investigation in his mouth.
The second vet was able to diagnose a small lump as a blocked salivary gland.
If he did need an operation then that could be costly due to the anaesthetic mainly I think. But you would still have the option to go back to pets at home to have the operation with them paying, after having another vet opinion. If he didn't need an operation though, and it just needed lancing or draining and antibiotics, then it might be better to stay with the vet you got the diagnosis from (ie the second opinion vet).
Just a thought.
Do you have a pet carrier by the way? A guinea pig sized one like this one is a good size as you can half fill it with substrate and put a little house in it for them to hide in
https://www.amazon.co.uk/Ferplast-Al...rplast+Aladino
That's the one I have but there's a Trixie one that's very similar and a bit cheaper. Around the same size.
When I take our hammy somewhere in his I take a fleece blanket to put over the top when we're travelling or sitting in the waiting room, and he just goes to sleep in there