Thanks all. Yes - I agree with the general consensus, I just wasn't sure if I'd create more problems by changing the standard overhead join such as I was then a problem for departing traffic from the active runway and wanted to check. On that last point - note while you're descending in either a high or low wing A/C, you're not always going to be visual with all traffic and you won't be on the same crosswind as a circuit crosswind - that's the point.
And yes - joining a circuit is different to joining any other british roundabout in that you generally can't stop in mid air and other 'cars' may be coming up from below....................