I agree with SouthernTrails
Horse camps are actually epic! You learn so much and they're really good fun. I've been the oldest at a couple I've been to and it made it more fun in some ways cz the younger kids look up to you, and you go back to your 10 yrold days and play around again!
You could try sweet-talking your parents into letting you stick around the stables you ride at for an hour or so before/after your lessons and gain experience that way. Ask the stables, but most are happy for the free help!
If you have to chose between camp and 6 weeks of lessons, and the stables is open to helpers, you could strike a deal with your parents where you miss those weeks during the schoool holidays, but cycle to the stables (if possible) and help during the holidays so you still get your horsey fix without paying for lessons!
(Oh and my local stables gives free lessons if you help out for a while *cheeky grin*)