Damn, I'm going to be in Ireland for the CTC AGM on the 25th. Otherwise I'd have come along to anything if there was an acf bash being organised.
I live just up the road in Ealing and if you want a cheapish place to stay, you could always look at the Travel lodge in Kew. It's a ten minute pootle to Mortlake from there, past Kew Botanical Gardens - one of my favourite places. Richmond's packed with good restaurants; you won't go hungry, that's for sure.
I think if I wanted to get from Heathrow to Richmond, I'd take the tube out to Hammersmith and change for the district line back to Richmond. Don't try to cycle it unless you're very determined. Pretty much any of the routes you could choose will be horrible.