I suspect there are many, but just flicking through the MTB inner tubes, there are some Conti tubes that are 1.1-1.3 which would be ideal for this tyre.
Continental Quality MTB Inner Tube
Presta 42mm 26x1.1-1.3 (Opt-C) @ £4.99
I bet there are others, its the width that is key.
5 years ago
New Forest, England