Welcome to the forum, and I hope to many years of enjoying cycling.

The Focus bikes always get good reviews. They seem to be very good value for money. Personally, I would recommend you get an aluminium framed bike (possible with carbon rear stays) with a good groupset (Shimano 105/Campag Veloce, or above). If this is going to be your only bike, and you intend to ride all year round, consider one that has clearance for mudguards.

Your local bike shop should be able to recommend the right bike, and advise you on fit. Since you are new to cycling I would suggest you speak to them, rather than buying over the net, simply because unless you know exactly that the geometry of the bike will suit you, it is very easy to buy the wrong size/geometry bike, and then try to fit your body to the bike, rather than the other way around. This will lead to injury.

As far as clubs go, the British Cycling website has a clubfinder, which will filter by region. Each club listed will have the secretary's contact details. Give them a ring and discuss your situation. You'll find out how welcoming they are that way, and you'll stand the best chance of joining the right club.

Good luck.