shame i'm not closer (Kent) else i would come out and give you a hand
try getting to the gym a few times on just a pay and use basis rather than a costly membership and they have the fixed exercise bikes so try these and just get into the rhythm of pedaling and the feel of a bike as they do feel some what different to anything else. you can pick up a cheap bike from a boot fair or off
ebay or so for max £50 i would say, when riding along i often see at the side of the road a cheap mountain bike with £10 or so written on it so keep an eye open
then find yourself a nice soft public green or friendly farmers field or so and whilst wearing a helmet (please, it will help when at least learning! oh and please no one start the war here!
) then simply try getting on and pedalling you will probably get a few meters feel un-steady and fall off, this is why you are in a soft grass field with a helmet
just keep trying and you eventually get the hang of it
i learnt when i was maybe 3 or 4 years old by my child minder taking me and my bike up to the local playing field and i did fall off and it did hurt but i now love whizzing down country lanes at 20 or 20 mph on a good day!
Cheers Ed