Chica - we bought a Chariot system (www.chariotcarriers.com) which I know you can get in the UK/Europe. The company was recently bought out by Thule. This is our first baby so I can't say for sure how great they are, but they are SUPER popular here in Alaska with the outdoorsy/active crowd and we have lot of friends who have kids who swear by them. You buy the chasis and then there are different kits that come separately (stroller/jogger/bike/ski). We got all but the ski one. We also got an infant sling to use when the little one is under 6 months.
Warning: the price tag on these is crazy - we got a huge discount b/c my husband works for an outdoor retailer. However, you might be able to find one used. Another thing, these are pretty big, so they wouldn't be good for taking on public transport.