will it be possible to buy t-shirt of the tour at the show ?

Yes mate having just come back from the Birmingham show I can confirm they are selling tour t-shirts at the merc stand at the shows. They sell out of the larger ones quick and no XXL but if XL will do you then get your t-shirt on the way in rather than waiting for the crush thereafter.

got a red one with yellow lettering, disappointing that there were no dates on the back.

Identical to the one I bought (and wore) in Liverpool.