Yew make great bonsai, however they are quite slow growing so it would take a very long time before yours has trunked up enough to be interesting material. At least up here in NY state they are a pretty popular landscape plant. There are a lot of old yews around here in people’s yards that look kinda “crappy” (Grown out of shape) that I’m sure plenty of people would be happy to get rid of. You may be better off hunting down an old landscape yew that somebody doesn’t want anymore. I feel like their foliage is a bit too coarse to look good with only a thin trunk usually.