Side return glass roof gap to outside world - needs filling Information, help and tips on many areas of roofing including trusses, tiling, venting, insulation etc....

[Simon Jinks]

Hello - I wonder if anyone could recommend a suitable product for the issue in the image attached? It's to fill that gap left by our disastrous builders on our side return extension roof where the concealed gutter meets the glass roof, or doesn't as the image shows. There's a roughly 30mmx30mm gap to fresh air outside which creates quite a draught and isn't weatherproof (not to mention flood proof if the gutter ever gets blocked). What would you recommend to fill the gap which offers the best properties ie weatherproof, good soundproofing, flexible fit and possibly an adhesive back on one side? There's a handy lip on the edge of the gutter of about 30mm so at least a good place for any insulation to sit/stick. Thanks in advance!