Moving out of London

I'm seriously considering making a move and would really appreciate any advice or experience anyone can share!

I've looked at all the normal London commuter areas, and then looked at some smaller, more rural places around the south east. None of them really appealed, but it did lead me to writing a list of what I do want:

• Lower cost of living, so I can afford to rent a 2 bed place (giving me a real space to WFH)
  
• Somewhere I don't need a car
  
• Big enough so that there's enough going on (restaurants, events, opportunities to meet people etc) and you're not doing the same thing every weekend
  
• Easier access to the countryside/mountains/coast/green spaces (any of those really, I'm just fed up of having to cycle for a rubbish hour just to get out of London)
  
• Maximum 2 hours or so from London by train so that I can still come in when work dictates
  
  

My research so far has narrowed it down to Cardiff...and that's about it. Has anyone spent much time there? I've never been and only know one person there so I don't know if I've just built it up in my head into what I want. Or any other recommendations on places that might be appropriate? I had considered Hove, but I think given the WFH situation I feel like now is the right time to try something different.

My main concern is that I need to make a decision soon due to my flat tenancy. I either decide by 10th December or I'm stuck where I am until June, which doesn't sound appealing.