What is a cheap but good bike for learning to ride on?

[It'sLiam:Ottt]

Ashamed to admit it haha, but I never learnt to ride as a kid, I was much more interested in computer games and the swimming pool. I am now 18 and still haven't learnt but would love too. Especially considering I love endurance sports and am missing out on a lot of cross-country bike trips.

I will probably learn on a secluded field somewhere to save myself embarrasment .

Thanks for any answers! Take care!