Try and talk them into a 3035. The gasket is big and will tuck in the joint nice its rubber so no need for insect mesh. The look is recessed so if you joints are horizontal. I guessing they are? Not ideal so you would want a drip also on the upper edge to deflect water away. It won't get past the rubber gasket but it could sit there stagnating unless you fill out the recess with sealant.
Loads of beads on the site tho I would have a good look in all the categories and see what you think. You want speed and price obviously. 30 quid a length is a joke. You might get a better price from a Wemico account holder rather than Wemico direct as they do hike upnprices for one of purchases.
Maybe jub can help you out ?