Hi Mrs T and welcome! We're newbies and have just taken on an allotment too.
I'd recommend getting your hands on a copy of Susan Berger's book 'Allotment Gardening, An Organic Guide for Beginners' - you should be able to find it in your local library, otherwise go to A4A's amazon shop & buy it there. It's a good beginners guide (funnily enough ;D ) and will give you plenty of info to get you started.
Of course, you'll find lots of friendly, helpful advice and answers here so ask away & good luck! x