A quick classification lesson may be in order... Roads beginning with:
M: (M1, M40, M62 etc) Motorways. Dual-carriageways - mostly 3 lanes in each direction but inclined to reduce to two lanes in less well-trodden areas - speed limit (theoretically
) 70MPH.
A: (A1, A40, etc) A-Roads. Major roads between towns. Generally, the smaller the number (A1, A2, A3 etc) the more "major" it is - the A234 for example may be no bigger than a typical "B" road where the A1 is little short of a motorway near large towns on its route. Usually wide single-carriageway but often becoming dual-carrigeway in and approaching large towns and on busy routes not covered by a motorway. Things change in more rural areas: in North Wales or the Lake District for example they may become 4 metres wide with a sheer drop on one side (with guard-rail) and a rock-face on the other... So, quite variable in practice.
B: (B52, B189, B3056 etc) your typical back-road used to join up the bits the A-roads miss out: smaller villages etc. In rural areas, inclined to drop down to just enough room for one car with passing places at intervals.
So, if in a rural area, I'd suggest you pick an A-road. B-roads tend to meander a bit so it can be difficult to keep track of where you are, or indeed which direction you are going in... Satnav comes in very handy!
In general, if going from A to B and not in a hurry, I'd just pick out a couple of stops on the way from a tourist guide and use whatever A and B roads get me there.
Roads are all paved - no dirt roads etc, even the sub-B roads so no worries there. They are often narrow in rural areas though. Smaller A and B roads were often originally cart tracks between villages and the surrounding field systems - then someone came along, shovelled tarmac over it and called it a road...
Have fun! Bob.