Advice: DIY flowers in London

Hello all! My London wedding is now one month away and I am getting ready to DIY my flowers (bouquets, bud vases, and buttonholes). Ideally, we would either pick them up or order them to have them delivered 1-2 days before the wedding and we have a space booked to do the assembly the day before.

My question is - has anyone done this in London before and where did you order/purchase your stems from?

I know about Covent Garden flower market but I don't love the idea of getting up at 4am the day before my wedding, so hoping that there might be another option that is not quite so early/overwhelmingly large. I am based in north London and have a car. Thank you in advance!!