This sort of ongoing network/atmosphere is great on one level but on another it doesn't really provide the pressure cooker 'kickstart' that something like YC does. I think we have all the ingredients for a YC, but they're too disparate right now, perhaps.
But your point is well taken, meetups are not a big problem, and the lack of them is relatively easy to overcome.
A proper YC clone probably requires (a)Angels, plural, successful ones, with personal experience of startups (b)20-50K per round, so assuming 2 rounds a year, and three years to get some form so others will back you thereafter, ~120K min.
I think that's it, and if you're lucky you could get away with less. Here, government might be useful. 60K isn't chickenfeed but it is doable in grant aid. If you could find someone willing to pony up 60K, you could get matching funds from a local authority somewhere in the UK, or from one of the enterprise incubators.
Sure, the YC dinners are weekly, no-holds-barred, and have a select audience, but if you have a proper YC clone going you will be able to get speakers on a weekly basis. Probably not of the same quality, or with the same ease, but you can get speakers. The other points fall under All discussions follow Chatham House Rules
added mine to mine. :)