thanks for all the advice, keep it coming. I have just got back from start fitness on grainger street (Newcastle). The guy was very knowledgeable and gave me some useful advice.
I think this is the direction I may end up going. From the discussion I have just had, it was suggested that I get a cyclo-cross. That one suggested was this merida cyclo cross 3
I haven't heard of that brand before. It was also suggested that I change the tyres to a thinner, more slick tyre. A one that was mostly rubber was mentioned but I missed the name, he said they were about £30 each. But also that kind of bike can easily be fitted with a rack.
The trouble is always going to be going past the A184. I think it is too fast a road to cycle on, and the path, whilst reasonably smooth, does have ridges and grooves were tree roots have pushed the tarmac, this would make a full road bike struggle.
that as something I have just discussed. However my mountain bike is will be too heavy to push it in that direction. I would rather have it as a proper mountain bike for when I got along the coast paths and a commute bike that does well on the road. Means if I damage my mountain bike, I can still get to work.