It's a big one.
On average, The Knowledge takes around four years to complete, although it can take longer depending on your circumstances.
There's also the financial side to consider. Most students buy a scooter because it saves a lot of time in the long run, but you'll also need to budget for fuel, insurance, maintenance, and all the other costs that come with owning one.
Also there's additional costs for your blue books and maps.
There's a social investment too. Nights out, weekends away, and holidays with your mates often have to take a back seat for a while. The good news is they'll still be there once you've qualified.
For me, it was one of the best investments I've ever made.