Zara man plain T-shirt would run you about £12, I’ve got a few that I’ve had for years. A pair of jeans would be about £30 and the pair I’ve got has also lasted me ages.
There’s a Zara in the town, one up Glasgow Fort, and they’ve got an online storefront here: https://www.zara.com/uk/en/man-basics-mkt587.html?v1=2112954