Cardiff to Bournemouth

[adrums1999]

Does anyone know the quickest route from Cardiff to Bournemouth? I've been on two sites claiming to give me the fastest route, but they are both completely different! Should I take Junction 18 off the M4 then go through Pennsylvania and then Bathampton, or should I go off the M4 at Junction 17 and down the A350 past Chippenham and Warminster? I'm travelling there in about 10 hours so a speedy reply would be appreciated! :o)

[FOUR STAR]

Off Junction 18 of M4 (as you say) the A36 towards Salisbury then A338 to Bournemouth.

I tried various routes and this is the quickest.