Please be advised there are foot/cycle paths on the "old" Severn Bridge (M48) in both directions that are well signposted and accessible from both sides. However there is No foot/cycle path on the new Second Severn Crossing.
Carrying bikes on the tube is explained by Transport for London here. You can only take bikes into stations that do not rely on escalators so I will have to take the district line from Wimbledon to Paddington to get the train to South Wales.
National Rail Enquiries publish information for cyclists here. First Great Western (Tel: 08457 000125 www.firstgreatwestern.co.uk) operate the trains from from London Paddington to Reading, Thames Valley, Bristol, South Wales, the Cotswolds, West of England plus Reading to Gatwick Airport:
High Speed Train services between London, South Wales and the West Country can accommodate up to six cycles and advance reservation is recommended, free of charge.
However, reservation is compulsory Monday – Friday for all services arriving at London Paddington between 0700 and 1000 and departing London Paddington between 1500 and 1900.
Now that I have all the information I need, I guess I need to start looking at my fitness, and perhaps as importantly that of my machine.
I'm lucky to live smack in the middle of the eleven and a half mile Wandle Trail walk and cycle route so on Saturday I plan to take it all the way South to East Croydon, then back to the North end at the Thames in Wandsworth before turning and riding back home.
That'll be a little shy of 25 miles but leaves me not too far from either a pub or my house should I or the bike run out of steam.
If that passes off without incident I will get the train to Reading on 1 July and cycle back to home from there. It's about a third of the way from SW19 to Cardiff so it will give me a better idea of how long I will have to spend in the saddle each day when I do the whole thing.