I am fortunate to live somewhere with easy access the sea, which means I've never got round to diving any of they UK's inland sites. Thanks to some vouchers I received as a gift from my lovely in-laws, MrsCyclops and I gave it a go today at in the former quarry at Capernwray.
It's very different to diving in the sea. There's generally much less life (especially on the rocks and bottom) but there are a few very large and very tame fish in the shallows. It's also pretty warm at this time of year, and with no current or waves it makes for very pleasant and easy diving. There are also other benefits such as nice changing facilites, and a cafe for a hot lunch. These luxuries are missing from the sort of lay-by I usually shore dive from!
A lovely day out.