Hi Chrisgp007,
I am Austrian and usually dive in our lakes with wet suits or dry suit. If you are not accustomed to dry suit diving, this would be an excellent opportunity to learn it here. And if you want to dive in a wet suit, as I did many times, I recommend to get a 7 mm plus a 3 mm shortie to wear under the full suit, as well as a hood and thick gloves and neoprene socks. This way, you should be able to stand the cold water quite well. I do not recommend the use of "ice vests", which are normally worn on top of the wetsuit, as they give very little extra thermal protection.
greetings
Markus