if you drive properly it won't be three and a half hours away, drive at 120mph at least and it'll be like what, an hour?
To be fair, it's a 3 and a half hour drive from where I live to get to Oakwood, and it's a 45 minute drive (30 minutes if I drive properly) to Alton Towers. And I would say it is WELL worth going to Oakwood to ride different stuff, so I guess it would be exactly the same thing for you... apart from the fact that you're talking about 2 much much MUCH better parks