In reply to MPSBunny:
I used to be in the LMC when I lived in London. I did a few trips to Scotland with partners from the club but generally found it quite hard to find regular partners on an adhoc basis when conditions were good. I'd recommend them nonetheless as the club were very active generally and it was easy meet members and socials/walls/meets.
The hardest thing with finding London partners for Scottish winter is that people need to be pretty psyched to drive 9 hours each direction in a weekend. Generally people with that level of psyche for Scottish winter don't live in London in the first place, so it felt a bit of a catch-22 for me.
Other major problem was finding people who could finish work early enough on a Friday to get to Scotland at a sensible time. Bearing in mind leaving in the heart of rush hour meant further delays. Eg a 6pm departure could easily result in a 4am arrival.
I did such trips for a few years but it really started to wear me down to be honest. When you get a good run with the traffic it's ok. Often there were significant delays at some point on the journey, which could easily add an hour or two. I crashed the car through sleep deprivation on one occasion on the return journey. Another occasion I took a big fall on a route, also related to sleep deprivation I reckon.
In summary I'd try to put yourself around as much as possible as regular Scottish climbers are a fairly rare breed. Join a London club, look for people on UKC, maybe look at the CC also. Last season before I moved away from London I was climbing with more people from the North, or from Scotland, and taking the train to eg Glasgow. It cost a bit more but the train was definately more relaxing and finding partners in eg Scotland much easier.