M4 closed at the weekend. We have planned on visiting Cardiff University. Any local people have advice about diversions and extra time it might take?

[YesRachelItIsMe]

We are travelling from Hampshire.
Does anyone local, know what the diversion might be and how crazy it might get?
There aren’t any further open days on the website and we need to think about whether we cancel the trip.

I know when the local motorway here has been closed, it has been best to stay well away.

Any help would be appreciated.

Is it ever great? Personally I’d go north, head across from J17.

Oh you mean take a loop around Chipping Sodbury etc?

I was vainly hoping that I'd misremembered the A303 and that it had improved somehow.

I was stuck in an A303 jam for so long one May half-term that some roadside cow parsley is still imprinted on my memory!