Nice, lovely looking bike. (Can anyone lend me 1600 quid?).Personally if I had £2k and wanted fancy / special, Decathlon would not be on my list. There is a big one on Purley Way however
GB and Pearsons etc will offer lots of help with spec and sizing
These are v pretty in the “plastic” and even around SW London you’ll rarely see on the road. They’ll spec it to your needs, unlike buying off the peg when you may need to change bars, stems, even cranks esp if buying men’s / ‘unisex’
https://www.pearsoncycles.co.uk/pearson-i-m-not-a-number.html