As you are Lincoln based, that's not a million miles away from Stoney. I run the East Midlands Underwater Photographers and one thing we are planning is to get someone up to Stoney, or nearby, to do taught courses over a weekend. This wont necessarily include diving, but will cover different aspects. Maria Munn is keen to do this for us, so if your wife fancies that then you are welcome to come along. We don't have membership, so you don't have to join (
www.emup.org.uk). As a group hopefully it will make things cheaper.
Rob