I've got a similar setup. I got some 5mm EPA foam and some adhesive velcro strips off amazon (prob £12 i reckon) and a heat mat and inkbird from malt miller. I've just set it running, i'll see how it goes over the next day or two.
My heat mat is under the bucket - how long do you think will take to go up 1.5C to the target temp?
Next job will be to get an under counter fridge off FB marketplace and make a FV chamber. Need to make some room in the garage first! :-)