No, go plumbing*. Spending a ton of money on a useless piece of paper is bonkers. The balance is the simple cost- benefit one. At the moment there is NO benefit in holding a perishable licence. Save your money, fly for fun (call it hour-building) and wait. If you're near the age limit, don't waste £120k. When it picks up, assess the cost-benefit again. If rich, ignore this and go round twice!
*spend 6 months on that, rake in some dosh.