If you’re using bucket method make sure it’s a v deep bucket!! Rats can jump about 3 feet high – so bear that in mind.
If you really really want to catch it you’re probably best going for a humane trap. As for how to get one… Er… maybe a local pest warden would lend you one for a few days for a small fee… Or a pet shop???
Domestic rats are just as clever as wild ones, so I wouldn’t worry too much about its chances out there. It’ll no doubt be rummaging through someone’s rubbish bin thinking that it has died and gone to heaven as we speak.