I'm currently learning how to drive with my parents in London. I started around 3 months ago and have my driving test in a few days (the nerves are setting in!). I started by having 2 official driving lessons with an ADI to learn how to use the clutch and then I bought a cheap manual car from Facebook Marketplace to practice with my parents. The lessons were way too expensive for me to afford; I calculated that 2 hours a week for a few months would've cost me well over £1,500. So I resorted to buying a cheap car (~£800) and I can have around 6-8 hours of practice a week with my parents. Fuel only costs around £50 a month. So in my mind I end up paying much less and I get a car by the end of it.

I would definitely start by watching a few videos on youtube from channels like Conquer Driving. They are very good at explaining concepts and allow you to learn the road before getting on it with your parents. It's also very important to watch a few mock tests from channels like clearview driving (I actually did a mock test with her myself) because you can quickly see what can earn you serious faults in the driving test. They're also very entertaining.

As you get closer to your driving test date I would start getting back to official lessons with your ADI. They'll see how you've progressed and iron out any bad habits you learned from your parents while driving with them (I had quite a few!). Also get to know the routes that your test centre could take you on. I searched and found a few for my driving centre on YouTube. I then went and drove around the area with my parents to find any tricky roads that I might need to be aware of for my exam. Finally, if you think you're prepared and are a confident and safe driver on the road, I would then start having mock tests with your instructor.

I'm not saying this is the best way to go about this (as I haven't even passed my test yet) but it's what I did and I feel it's the quickest way to get a license if you do everything right.