Not sure which one to mean,one of the m/cycle shops or one of the other shops that sell bike gear,some shops are only 'temporary' for TT week.....a list of all the UK dealers can be found here;
http://www.phoenixnw.co.uk/dealers.html For all things Arai,try these fellas;
www.thevisorshop.com Ise of Man motorcycle dealers;
http://www.begin-motorcycling.co.uk/d_iom.htm