I reckon 2 hours in those conditions is about as good as you will get, unless you go 5mm, hoodie and maybe booties.
Have a look here for some general comments
https://surfing-waves.com/equipment/ ... -guide.htmAnyway, can't help you with a specific suit. Just keep in mind that the further you go up the price range, the more flexible and stretchier the material will be, but it wont necessarily be warmer (some have 'quick drying' type insides). However, better stitching systems etc will minimise water getting in.
So basically you don't need an ultra expensive wetsuit to stay warm, a cheaper one will do. However, the cheaper one will be stiffer and less stretchy and will makes things slightly harder in terms of paddling, bending etc. Also you need the cut to be more suited to your size; stretchier suits will stretch to fit you.
Chest zips assist in flexibility, because you cant stretch a zip. If you have a big zipper running up your back, then that prevents any stretch along where the zip is; whereas a chest zip doesn't (only prevent horizontal/up and down stretch, which doesn't really matter). However, chest zips tend to be pricier. Still, if you are going to use it for other sports, consider it (as you probably know, a surfing wetsuit isn't very suited for swimming)
After all that - my only tip is go into a store and try them on. All wetsuits are cut slightly differently. I had to try on 6 or 7 different brands before I found one that fit me (I'm tall and thinnish - apparently for my height my stomach is meant to be considerably larger). A brand that works for one person may not even fit someone else, even of the same height. After your board, your wetsuit is the only other thing you need to surf, so its worth spending a bit of time trying to get the right one even with a limited budget.
Any of the big names will make good suits. There are undoubtedly cheaper brands/non brands that make perfectly good suits as well, but these may be a bit riskier.
I cant see a 3/2mm suit being sufficient. Yes when its 17deg, but not when its 12. I doubt ever getting too hot will be a problem, so you may as well buy a suit for the coldest time and then just wear it in summer - you wont get too hot (and if you do, then use your current suit for summer). Your other option, as per the link above, is maybe a 3/2 suit plus another top; but I reckon 4/3 is the way to go with a second top if you need it. Of course, I'm in Australia and if it gets to 16deg water temp where I surf we complain long and hard, so what do I know (other than I'm so glad I don't surf in the UK) .