I got to admit I'd much rather be diving in a 3mm shorty than a dry suit, but not possible in the UK lol.
Bloody annoying about that dive shop closing on you, but if you have to do it again atleast you should breeze through it now. Have you still got you book? that could save a bit of time and money if you do it again.
I think dry suits are one of those things that grows on you. Most people I know that own dry suits rave about them and even use them in warm water..
If you are wanting to do something before the water warms up enough for wet suits you could always look at a non diving spec like equipment. I found it quite interesting to see the insides of 1st/ 2nd stages.
Oh and as you are interested in wrecks, they are putting another wreck into stoney. A trawler called MV Belinda is going in at 20m. They have put there prices up at stoney now though