Take your time.
Getting your first suit made takes time. It requires multiple fittings and adjustments – you can't just go to London for a week and come back with a suit. Most tailors will measure you once and then make a loosely mocked-up coat that you try on during your second fitting. Then they'll make the necessary adjustments so that your jacket fits comfortably on the third attempt. Even then, better tailors may still adjust the length. Proportions are everything.
Next time you need a suit, your tailor will have all the details on file and can make something much more quickly. This is a sartorial blessing and a budgetary curse – rare is the man who gets a bespoke suit and doesn't come back for more.