where to find clothes for toddler with eczema

[starfish2]

I need to find plain white or yellow T-shirts for dd (nursery requirement...), 100% cotton or bamboo, because dd (2yo) has eczema. Winter is coming, so I would like to get them with both short and long sleeves. The nursery wants yellow, but I can get away with white long sleeves under yellow short sleeves.
I have tried H&M, M&S, John Lewis, Next, Adams, Woolworths and Mothercare. None of them have plain T-shirts, everything is either polycotton (nono) or not plain.
A web search so far shows expensive stuff (£10 and over), and since it is not for anything fancy (and I'll need to get several) I would prefer not to spend a small fortune on them... Any suggestions of where to find them?

I found plain white t's in mothercare maybe they have sold out

did you look in the boys section too?

I looked everywhere, girls and boys. Asked the shop assistants, and they all told me 'not in this shop'.
I am still surprised at how difficult it is to find plain t-shirts. I thought it was a very common thing, but obviously it is not. Very frustrating.

green Baby"Look at baby"

cut 4 cloth
"cut4cloth cut4cloth"

all good retailers my wee one has eczema, and these were fabby

green baby
"Look at green baby"