Hello From Cambridgeshire.
Sorry not very knowledgeable about the eastern reaches of Suffolk, and Suffolk seem to be one of the few LA that have yet to put an online copy of the definitive map for their council tax payers
But here are a couple of resources to help you along:
The guys who runs this site requests data from the Local Authority, some of it is a bit old now so could be out of date. But atl elast you can identify BOAT (blues lines) to check out in more detail.
http://www.rowmaps.com/showmap.php?place=Ipswich&map=OS&lat=52.0571&lon=1.15285&lonew=EHere you can find P/T-TRO Permanent/temporary traffic regulation orders i.e. rights of ways which are now restricted, you can use this to eliminate lanes that are closed to motors (m/c may be excluded)
http://publicrightsofway.onesuffolk.net/home/traffic-regulation-orders/permanent-tro-map-plots/As per other advice joining up and getting in touch with others in Suffolk is the fastest way to avoid a lot of painstaking research. You are always welcome to come over to Cambridgeshire to we a quite a big group and have a great network of lanes we use including around thetford.
Regards
Adrian