hi ispartacus, welcome to the club lol. best thing is follow the link pswoff put up and read up on how the scheme works, have a look at the car search tool on there and see whats available.
i would sit down and make a list of what you need the car for, have you family, are you a wheelchair/scooter/walker user, do you need a higher driving position,do you need driver aids etc.boot size.
then what aids would help you, keyless,cameras,sensors,automatic etc.
then its a case of working through which cars fit your needs,test driving and then the nitty gritty of working out how long for delivery etc.
and you thought it would be easy lol.
anyway during and after all that if you,no when you have questions either just ring motability they are very helpful or ask on here theres always someone thats had the problem before you.
have fun.