I already have a thread that covers latency to OVH London and France on the 1gbps service. Just like pretty much anything else, full line speed is also fine since the routing is good. I have the 2gbps service now but can’t check as I’m away from home, but I wouldn’t expect any difference. https://talk.yayzi.co.uk/t/yayzi-vs-bt-fttp-speeds-routing/
As soon as you’ve entered OVH’s network in London the routing is on them so Netherlands should also be fine.