I am planning for my retirement, and am hoping to be on my pension when I am 38. I'm single and don't have any commitments (no kids, relationships etc.).

My budget is around 4,100 per month, and I have been saving for either a house, or in this case a yatch.

Thoughts? Do you know anyone who does this or help me find some reliable info (books, youtube etc.) on doing this? What is it like realistically?

No - That price is crazy;
a local supplier has it at around $105 for 8' x 4' 18mm - and they are not known for good prices.

Online, $70 for a single sheet or $60 each in bulk..

(Those are for full specification marine grade).