Swimming:
- Virgin Active has two decent 25m pools fairly near St Pancras (Angel Islington and Bunhill Row), I used those when I lived in Islington
- Some public Pay-as-you-go pools (Pancras Square Leisure Center, Ironmonger Lane, Queen Mother Sports Center) and the London Aquatics Center (The Olympic swimming venue, I guess one should try this at least once while in London, although I haven't yet; need to pre-book)
- The Serpentine lake is open during May - September and is remarkable quiet (~100m length in a cordoned off aera) and year round early mornings for Serpentine Swimming Club members, probably worth the £20 membership just for the Christmas Day Race (sans wetsuit)
- There are some lakes near Heathrow (Thorpe lake and others) that are open for open water swimming during the summer with loops of different length up to 1500m.
- Otter Swim Club - Coached Sessions in several locations across the city, pretty expensive (~$1000 p..a.)
- I swim at David Lloyd Kensington and occasionally at DL Fulham (both 20m pools)
- There are some other outdoor pools / Lido's, but never been to any of them (
http://www.serpentine.org.uk/...e_tri_openwater.html)
Cycling:
- If you're near St Pancras you can cycle around Regent's Park, ~4.5km loop with few intersections, or a 1k loop in the center of Regents Park, if you are training for a Deca-Ironman. Just need to be careful with stressed out parents parking around the zoo without paying attention to traffic, but plenty of cyclists there
- Richmond Park is great early mornings and late evening (you can cycle with bike lights after they close the gates for cars), cyclists love to race triathletes on TT bars, lots of posing in the cafeat Roehampton Gate,20 mph limit applies to cyclists as well and police regularly show up with radar equipment
- Plenty of nice rides to the Surrey Hills (mostly undulating with a few hills, some short and sharp with up to 20% incline, Box Hill and Leith Hill are the major climbs in the area) and to and around Windsor - I can dig out some GPS files if you're interested. Quo Vadimus has listed most of the climbs I know, would only add White Down Lane in Dorking to that.
- London Dynamo is the biggest (I think) bike club in London with plenty of group rides
- I mostly cycle indoors nowadways except for long rides, getting out of the city from the St. Pancras area is going to take time unless you're heading for Regent's Park loops
- London is not the safest place to ride with ~15 deaths per year and ~400-600 serious injuries
Running:
- Around St Pancras area mainly along the Regents Canal (have to navigate with pedestrians and cyclists, especially under the low bridges; if you run west, the Camden Market area is a bit shitty), Regent's Park and Victoria Park for longer runs
- There are low key monthly 10k runs (Regents Park 10k series) which are good to benchmark progress/fitness
- Hyde Park is good for running (maybe a bit far for you if you aim for Kings Cross/St Pancras area), also along Embankment / St James Park / Green Park or towards Battersea Park
- I run in Hyde Park, Battersea Park and very occasionally in Richmond Park, if I can find the time to drive there - I love Richmond Park, soft underground and undulating with a 10.5k or so loop
- Park Run has weekly 5k races free of charge organized in different parks across the country (
http://www.parkrun.org.uk). I run at Fulham Palace
.
Tri Clubs:
- Ful-On-Tri in Fulham
- Serpentine Running Club (loosely Hyde Park based) - there used to be a fairly large triathlete community when I was a member in 2005 - 2008 with organized group rides / swims etc., not sure what it's like now
- others:
http://www.triathlonengland.org/...ake-part/find-a-club In my opinion, the further west you go, the easier it gets, around Hyde Park is probably the best compromise, other than that close to Richmond Park or Putney is great for outdoors, but quiet far from the city center. Happy to meet up and go for a ride / run when you're here - PM me if interested
Hope your wife has an ex-pat package with rent paid by her employer :-).