It's just called a door seal, have a look at this website www.apart4u.co.uk, this will give you prices for your particular model and will also show you short a video clip, on how to carry out this sort of repair. It can be a tricky job, so watch the clip then decide if you feel confident enough to do it yourself.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix washing machines.