Dell, you're riding right through my patch there; I work between Bury and Manchester and live a stone's throw off the A666 as it heads towards Clitheroe from the Blackburn ring road. In fact my house would be a convenient stopping point for repairs, coffee, comfort stops or anything else, being in Knowsley Road, which cuts the corner between the A666 and the Ribchester road, avoiding the junction at the Wilpshire Hotel where the roads split.
I will certainly join you for the ride and will take a day off work to join you for one of the recces if you like.
Edit: just realised that your Watling Street route is the so-called Roman Road from Edgworth heading NW to Darwen. I strongly advise against this, if you study your map you'll see that it has two MONSTER gullies to cross, it drops a couple of hundred feet then climbs steeply and painfully out again, it really isn't a pleasant road and you expend an awful lot of valuable energy, twice, for absolutely no overall gain.
The A56 heading north out of Manchester is a good route then from Bury you can climb more easily through Holcombe, Holcombe Brook, Helmshore (great textile museum with cafe, hidden from the road for bike security) thence over the Haslingden Grane Road, a much better turnpike with fantastic scenery and so lonely that illicit hooch was once distilled there, and down into Blackburn. Straight on up the A666, past my place, Ribchester, Longridge, etc. In daylight at least you'll enjoy the Bury northwards section; there's some good mill scenery. You could divert through Summerseat and have a look at the beautiful Brooksbottoms Mill and the so-called "brick houses" built to house the workers, all now gentrified and rather bijou.
From the top of the Grane road you will be able to see a vast panoramic sweep from the
Ribble estuary right up to Blackpool tower, Morecambe Bay and the south Lakes, it's spectacular. At night you can see the lights of three radio masts at Inskip on the Blackpool route, which will look frighteningly far away!
I'm actually not sure there is a cafe in Ribchester though there must be one or two in Longridge.