Clear silicon washer pipe from motor spares cut down middle slip on window , no glue needed should do it or B&Q
aint Rs components 15 mins away ??? if we use grommet strip we get if from them normal wsalers stuff is pants and falls off.
http://www.amazon.co.uk/Shower-Scre..._UL160_SR160,160_&refRID=1BK4HC582BSWBW7VQ740 http://www.amazon.co.uk/HNNHOME-Bath-Shower-Screen-Glass/dp/B00NTVISC4/ref=sr_1_8?s=kitchen&ie=UTF8&qid=1457043316&sr=1-8&keywords=shower+seal+4mm I think these two links will set you on the right path mate. One is ready to go straight on with a rounded profile, and the other just needs a sharp stanley to take off the flap part. Up to you, but both will do the job. Others are available in a multitude of 'flap' positions, have a look.
http://www.amazon.co.uk/dp/B012WXZ1L0?psc=1 this is the other one most similar to that which you posted originally.
i used this... http://www.amazon.co.uk/gp/product/B00O048M4I?psc=1&redirect=true&ref_=oh_aui_search_detailpage worked really well