The gym work would not go amiss, but the bigger problem is that you will be sitting on the saddle for longer than you want. get out and ride for 2 to 3 hours nonstop in preparation. You will not be overwhelmed, but the fatal thing is to get dragged into a group that are just a bit faster than you want at the start. Start a little bit slower than you normally would for a few miles, and get your legs and lungs in. You will not be the only one new to this sort of ride and if you did fall unclipped , you would not be the only one to do so

Prepare for the ride the week before by carbo-loading. make most of your meals pasta, rice, sticky buns etc.Then the night before have another good meal and if possible a good breakfast a couple of hours before the ride. Drink- obviously fit two bottles on the bike or a camelback. Food to take on the ride is easy- whatever you fancy providing it is carbo hydrate and a little protein. Slices of fruit cake, cereal bars, small packs of dried fruit and I normally take a couple of bite sized chunks of cheese. Anything except power bars.

Clothes. It will be spring so normal cycling clobber but at the start have an overtop that will pack down if it gets warm, or a good waterproof if wet. Problem may be that if it is raining and cold, you may have to put an extra layer on, but you can always unzip. I did one horrendous ride in 2001 or 2 where it rained all day with gale force 9 winds that were always in the face although it was a circular route. Hypothermia set in and I learnt then that a complete change of clothing in the car is a good idea, along with an extra jersey and warm coat.

These organised rides are fantastic fun. It does not matter what speed you are, there is always someone around you on the ride, plenty of company and plenty of help if problems arise. For a century ride I would not carry any extra tools or spares but I would get the bike checked a month beforehand so that any cables will stretch or wrongly repaired parts will bbecome evident. Oh final thing-- get your entry in now, then there is no backing out. Enjoy.


(Edit) From Jazz cyclist's posting. Most of the problem is mental. on the drink side -take plenty even down to taking 1 full bottle in the half hour before the start. Food is important and I find that I run out of energy at the 6 hour mark if I have not topped up on the ride.