Agree with "forwhatitsworth", since the hard shoulder has been in use as an extra lane the section through to the M5 has got much better. Can't say there will be no congestion on a Bank Holiday but worth considering sticking on the M6.
M6 toll is a very long way round and you will get stuck on M42 near solihull. M6 has improved now with the hard shoulder being used or get off at junc 12 and follow A449 down through wolves and kidderminster, will take about 45 50 minutes
by taking the m6 toll or you will be doing is putting yourself into traffic on the m42, youll hit the back of that and queue just as long that way as you would just heading straight down the m5,