Welcome Jules,
I developed about 80% of my dancing out of training dvds, I had no choice, I have to drive 2, to 4 hours to get any instruction, or flight for 6 to make it to one of the big salsa center.
As a follow, you should get down the basics, but really get them down, then you will be able with some practice to follow good and average leads, training with a partner or social dancing is a must but before that basics need to be there so you can develop a sound technical base.
London, hmm so I think you will be on1.
basics that you should learn
-front back basic ( also call mambo step)
-side basic
-back basic ( push and pull)
-cumbia basic
-Cross Body Lead (CBL) FOOTWORK - yes there is actual steps, you can wing it, but only if you do the steps you will achieve control, timing and lightness in the dance floor
-CBL inside and outside turns footwork
-Right and Left (full and half ) Axels
-Right and left turns
- Work on single spins, but eventually work if possible to doubles
-get your hands off your sides, they should be moving up and around in nice styling leaving your sides available for the lead to get in close holds through out the dance
-learn, train to look at the person who are dancing with in their eyes, smile and have good time
dvds that I will recommend for on1 are liquid silver and salsa freak, beginners and intermedium 1. there are certainly others, I know you guys/gals have Leon Rose himself there, haven't seen his videos but his dancing is amazing