It does sound like the bedding is probably cotton so not worth the risk really, he should be fine with shredded toilet tissue, they usually love it.
The food doesn’t sound suitable, there aren’t any dwarf specific mixes available in the uk unfortunately & most of the mixes sold in pet shops aren’t good.
You can get good food from Rodipet, delivery costs aren’t too high & you can always get a few bags at a time & store it in the freezer to cut down on costs.
https://www.rodipet.co.uk/pet-foods/...nior-500g.html
Try to give him more green veg rather than the sweeter veg or fruit as they’re prone to diabetes it is best to avoid sweeter foods.
Most love broccoli, cucumber, green beans, lettuce, things like that.
Edit, I forgot about the cage!
Most cages sold in pet shops are usually too small & not suitable for hamsters.
A good cage for a dwarf is the hamster heaven although it’s best used without the tubes & penthouse that come with it (blockers are provided for the holes) it’s a good size, the base is deep enough for a good amount of substate & it’s high enough to fit an 8 or 9” wheel without being too high & posing a fall risk.
They don’t climb well so floor space is the most important thing for them with a good size house & smaller hides, coconuts are good & cork tubes or tunnels are great as both hides & something to climb over & explore.
You can get the hamster heaven cage from Zooplus
https://www.zooplus.co.uk/shop/small...YaAk5CEALw_wcB
or amazon
https://www.amazon.co.uk/Savic-Hamst.../dp/B003QRPAR2
Have a look through this thread for ideas on cages & set ups.
Let's see your cages - New thread - July 2017