Near Weston-super-Mare, a new bypass is under construction: the Banwell bypass. Some details from the local council
here.
There has also been news that either a new junction for the M5 motorway is under consideration or expanding and upgrading one or more existing junctions. Both ideas being for the northern part of Somerset / southern part of North Somerset area.
The U.K. currently has difficulty maintaining it's existing road network, so if more roads are built, that will encourage even more road traffic. And make road maintenance even more difficult and costly.
Although the U.K. population rate of growth has reduced compared to recent years, the general number of people travelling overall is I believe continuing to grow. I've not searched to try to find figures for this though.
So I believe this country should be both increasing the capacity and service frequency on existing railway lines, using existing freight lines for passenger traffic where it's beneficial for the community and building new lines where there is the potential for a reasonable amount of demand (even if the projected figures may indicate that such a line may not break even for many years).
In general, it's normally less expensive to build a railway line compared to a road for the same capacity and a railway line uses less land. There are also advantages for the environment for a railway vs. a road.
So it follows that greater cooperation between private railways and the national railway system should be something that is seriously considered.
This country really does need to do a whole lot more to encourage far more people to use public transport (both trains and local authority run bus services).
The existing mess left by all the years of Conservative government is just not good enough. The private bus company (First) ideas of running a reliable service are a standing joke on some routes.